diff --git a/backend/routers/roster_edit.py b/backend/routers/roster_edit.py
index 9bb62b1..0c2d974 100644
--- a/backend/routers/roster_edit.py
+++ b/backend/routers/roster_edit.py
@@ -9,12 +9,20 @@ import httpx
 import os
 
 from backend.database import get_db
-from backend.models import RosterUnit, IgnoredUnit, Emitter, UnitHistory
+from backend.models import RosterUnit, IgnoredUnit, Emitter, UnitHistory, UserPreferences
 from backend.services.slmm_sync import sync_slm_to_slmm
 
 router = APIRouter(prefix="/api/roster", tags=["roster-edit"])
 logger = logging.getLogger(__name__)
 
+
+def get_calibration_interval(db: Session) -> int:
+    """Get calibration interval from user preferences, default 365 days."""
+    prefs = db.query(UserPreferences).first()
+    if prefs and prefs.calibration_interval_days:
+        return prefs.calibration_interval_days
+    return 365
+
 # SLMM backend URL for syncing device configs to cache
 SLMM_BASE_URL = os.getenv("SLMM_BASE_URL", "http://localhost:8100")
 
@@ -185,11 +193,11 @@ async def add_roster_unit(
         except ValueError:
             raise HTTPException(status_code=400, detail="Invalid last_calibrated date format. Use YYYY-MM-DD")
 
-    # Auto-calculate next_calibration_due (1 year from last_calibrated)
-    # This is calculated internally but not shown to user (they just see last_calibrated)
+    # Auto-calculate next_calibration_due from last_calibrated using calibration interval
     next_cal_date = None
     if last_cal_date:
-        next_cal_date = last_cal_date + timedelta(days=365)
+        cal_interval = get_calibration_interval(db)
+        next_cal_date = last_cal_date + timedelta(days=cal_interval)
     elif next_calibration_due:
         # Fallback: allow explicit setting if no last_calibrated
         try:
@@ -522,11 +530,11 @@ async def edit_roster_unit(
         except ValueError:
             raise HTTPException(status_code=400, detail="Invalid last_calibrated date format. Use YYYY-MM-DD")
 
-    # Auto-calculate next_calibration_due (1 year from last_calibrated)
-    # This is calculated internally but not shown to user (they just see last_calibrated)
+    # Auto-calculate next_calibration_due from last_calibrated using calibration interval
     next_cal_date = None
     if last_cal_date:
-        next_cal_date = last_cal_date + timedelta(days=365)
+        cal_interval = get_calibration_interval(db)
+        next_cal_date = last_cal_date + timedelta(days=cal_interval)
     elif next_calibration_due:
         # Fallback: allow explicit setting if no last_calibrated
         try:
@@ -1007,9 +1015,10 @@ async def import_csv(
                 if row.get('last_calibrated'):
                     last_cal = _parse_date(row.get('last_calibrated'))
                     existing_unit.last_calibrated = last_cal
-                    # Auto-calculate next_calibration_due (1 year from last_calibrated)
+                    # Auto-calculate next_calibration_due using calibration interval
                     if last_cal:
-                                        existing_unit.next_calibration_due = last_cal + timedelta(days=365)
+                        cal_interval = get_calibration_interval(db)
+                        existing_unit.next_calibration_due = last_cal + timedelta(days=cal_interval)
                 elif row.get('next_calibration_due'):
                     # Only use explicit next_calibration_due if no last_calibrated
                     existing_unit.next_calibration_due = _parse_date(row.get('next_calibration_due'))
@@ -1048,6 +1057,14 @@ async def import_csv(
 
                 results["updated"].append(unit_id)
             else:
+                # Calculate next_calibration_due from last_calibrated
+                last_cal = _parse_date(row.get('last_calibrated', ''))
+                if last_cal:
+                    cal_interval = get_calibration_interval(db)
+                    next_cal = last_cal + timedelta(days=cal_interval)
+                else:
+                    next_cal = _parse_date(row.get('next_calibration_due', ''))
+
                 # Create new unit with all fields
                 new_unit = RosterUnit(
                     id=unit_id,
@@ -1062,12 +1079,8 @@ async def import_csv(
                     coordinates=_get_csv_value(row, 'coordinates'),
                     last_updated=datetime.utcnow(),
                     # Seismograph fields - auto-calc next_calibration_due from last_calibrated
-                    last_calibrated=_parse_date(row.get('last_calibrated', '')),
-                    next_calibration_due=(
-                        _parse_date(row.get('last_calibrated', '')) + timedelta(days=365)
-                        if _parse_date(row.get('last_calibrated', ''))
-                        else _parse_date(row.get('next_calibration_due', ''))
-                    ),
+                    last_calibrated=last_cal,
+                    next_calibration_due=next_cal,
                     deployed_with_modem_id=_get_csv_value(row, 'deployed_with_modem_id'),
                     # Modem fields
                     ip_address=_get_csv_value(row, 'ip_address'),
diff --git a/backend/routers/seismo_dashboard.py b/backend/routers/seismo_dashboard.py
index 6f99d6d..7e48f83 100644
--- a/backend/routers/seismo_dashboard.py
+++ b/backend/routers/seismo_dashboard.py
@@ -3,6 +3,8 @@ Seismograph Dashboard API Router
 Provides endpoints for the seismograph-specific dashboard
 """
 
+from datetime import date
+
 from fastapi import APIRouter, Request, Depends, Query
 from fastapi.responses import HTMLResponse
 from sqlalchemy.orm import Session
@@ -49,10 +51,14 @@ async def get_seismo_stats(request: Request, db: Session = Depends(get_db)):
 async def get_seismo_units(
     request: Request,
     db: Session = Depends(get_db),
-    search: str = Query(None)
+    search: str = Query(None),
+    sort: str = Query("id"),
+    order: str = Query("asc"),
+    status: str = Query(None),
+    modem: str = Query(None)
 ):
     """
-    Returns HTML partial with filterable seismograph unit list
+    Returns HTML partial with filterable and sortable seismograph unit list
     """
     query = db.query(RosterUnit).filter_by(
         device_type="seismograph",
@@ -61,20 +67,52 @@ async def get_seismo_units(
 
     # Apply search filter
     if search:
-        search_lower = search.lower()
         query = query.filter(
             (RosterUnit.id.ilike(f"%{search}%")) |
             (RosterUnit.note.ilike(f"%{search}%")) |
             (RosterUnit.address.ilike(f"%{search}%"))
         )
 
-    seismos = query.order_by(RosterUnit.id).all()
+    # Apply status filter
+    if status == "deployed":
+        query = query.filter(RosterUnit.deployed == True)
+    elif status == "benched":
+        query = query.filter(RosterUnit.deployed == False)
+
+    # Apply modem filter
+    if modem == "with":
+        query = query.filter(RosterUnit.deployed_with_modem_id.isnot(None))
+    elif modem == "without":
+        query = query.filter(RosterUnit.deployed_with_modem_id.is_(None))
+
+    # Apply sorting
+    sort_column_map = {
+        "id": RosterUnit.id,
+        "status": RosterUnit.deployed,
+        "modem": RosterUnit.deployed_with_modem_id,
+        "location": RosterUnit.address,
+        "last_calibrated": RosterUnit.last_calibrated,
+        "notes": RosterUnit.note
+    }
+    sort_column = sort_column_map.get(sort, RosterUnit.id)
+
+    if order == "desc":
+        query = query.order_by(sort_column.desc())
+    else:
+        query = query.order_by(sort_column.asc())
+
+    seismos = query.all()
 
     return templates.TemplateResponse(
         "partials/seismo_unit_list.html",
         {
             "request": request,
             "units": seismos,
-            "search": search or ""
+            "search": search or "",
+            "sort": sort,
+            "order": order,
+            "status": status or "",
+            "modem": modem or "",
+            "today": date.today()
         }
     )
diff --git a/templates/partials/devices_table.html b/templates/partials/devices_table.html
index ac48044..e0dafe5 100644
--- a/templates/partials/devices_table.html
+++ b/templates/partials/devices_table.html
@@ -115,10 +115,10 @@
                                 </div>
                             {% endif %}
                         {% else %}
-                            {% if unit.next_calibration_due %}
+                            {% if unit.last_calibrated %}
                                 <div>
-                                    <span class="text-gray-500 dark:text-gray-500">Cal Due:</span>
-                                    <span class="font-medium">{{ unit.next_calibration_due }}</span>
+                                    <span class="text-gray-500 dark:text-gray-500">Last Cal:</span>
+                                    <span class="font-medium">{{ unit.last_calibrated }}</span>
                                 </div>
                             {% endif %}
                             {% if unit.deployed_with_modem_id %}
diff --git a/templates/partials/roster_table.html b/templates/partials/roster_table.html
index 31d1731..51f0d66 100644
--- a/templates/partials/roster_table.html
+++ b/templates/partials/roster_table.html
@@ -108,10 +108,10 @@
                                 <div class="text-gray-500 dark:text-gray-500">{{ unit.hardware_model }}</div>
                             {% endif %}
                         {% else %}
-                            {% if unit.next_calibration_due %}
+                            {% if unit.last_calibrated %}
                                 <div>
-                                    <span class="text-gray-500 dark:text-gray-500">Cal Due:</span>
-                                    <span class="font-medium">{{ unit.next_calibration_due }}</span>
+                                    <span class="text-gray-500 dark:text-gray-500">Last Cal:</span>
+                                    <span class="font-medium">{{ unit.last_calibrated }}</span>
                                 </div>
                             {% endif %}
                             {% if unit.deployed_with_modem_id %}
diff --git a/templates/partials/seismo_unit_list.html b/templates/partials/seismo_unit_list.html
index c1187e8..ac9ba15 100644
--- a/templates/partials/seismo_unit_list.html
+++ b/templates/partials/seismo_unit_list.html
@@ -1,13 +1,92 @@
-{% if units %}
+{% if units is defined %}
 <div class="overflow-x-auto">
     <table class="w-full">
         <thead class="bg-gray-50 dark:bg-slate-700 border-b border-gray-200 dark:border-gray-600">
             <tr>
-                <th class="px-4 py-3 text-left text-xs font-medium text-gray-700 dark:text-gray-300 uppercase tracking-wider">Unit ID</th>
-                <th class="px-4 py-3 text-left text-xs font-medium text-gray-700 dark:text-gray-300 uppercase tracking-wider">Status</th>
-                <th class="px-4 py-3 text-left text-xs font-medium text-gray-700 dark:text-gray-300 uppercase tracking-wider">Modem</th>
-                <th class="px-4 py-3 text-left text-xs font-medium text-gray-700 dark:text-gray-300 uppercase tracking-wider">Location</th>
-                <th class="px-4 py-3 text-left text-xs font-medium text-gray-700 dark:text-gray-300 uppercase tracking-wider">Notes</th>
+                {% set next_order = 'desc' if (sort == 'id' and order == 'asc') else 'asc' %}
+                <th class="px-4 py-3 text-left text-xs font-medium text-gray-700 dark:text-gray-300 uppercase tracking-wider cursor-pointer hover:bg-gray-100 dark:hover:bg-slate-600"
+                    hx-get="/api/seismo-dashboard/units?sort=id&order={{ next_order }}&search={{ search }}&status={{ status }}&modem={{ modem }}"
+                    hx-target="#seismo-units-list"
+                    hx-swap="innerHTML">
+                    <span class="flex items-center gap-1">
+                        Unit ID
+                        {% if sort == 'id' %}
+                        <svg class="w-4 h-4 {% if order == 'desc' %}rotate-180{% endif %}" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                            <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M5 15l7-7 7 7"></path>
+                        </svg>
+                        {% endif %}
+                    </span>
+                </th>
+                {% set next_order = 'desc' if (sort == 'status' and order == 'asc') else 'asc' %}
+                <th class="px-4 py-3 text-left text-xs font-medium text-gray-700 dark:text-gray-300 uppercase tracking-wider cursor-pointer hover:bg-gray-100 dark:hover:bg-slate-600"
+                    hx-get="/api/seismo-dashboard/units?sort=status&order={{ next_order }}&search={{ search }}&status={{ status }}&modem={{ modem }}"
+                    hx-target="#seismo-units-list"
+                    hx-swap="innerHTML">
+                    <span class="flex items-center gap-1">
+                        Status
+                        {% if sort == 'status' %}
+                        <svg class="w-4 h-4 {% if order == 'desc' %}rotate-180{% endif %}" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                            <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M5 15l7-7 7 7"></path>
+                        </svg>
+                        {% endif %}
+                    </span>
+                </th>
+                {% set next_order = 'desc' if (sort == 'modem' and order == 'asc') else 'asc' %}
+                <th class="px-4 py-3 text-left text-xs font-medium text-gray-700 dark:text-gray-300 uppercase tracking-wider cursor-pointer hover:bg-gray-100 dark:hover:bg-slate-600"
+                    hx-get="/api/seismo-dashboard/units?sort=modem&order={{ next_order }}&search={{ search }}&status={{ status }}&modem={{ modem }}"
+                    hx-target="#seismo-units-list"
+                    hx-swap="innerHTML">
+                    <span class="flex items-center gap-1">
+                        Modem
+                        {% if sort == 'modem' %}
+                        <svg class="w-4 h-4 {% if order == 'desc' %}rotate-180{% endif %}" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                            <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M5 15l7-7 7 7"></path>
+                        </svg>
+                        {% endif %}
+                    </span>
+                </th>
+                {% set next_order = 'desc' if (sort == 'location' and order == 'asc') else 'asc' %}
+                <th class="px-4 py-3 text-left text-xs font-medium text-gray-700 dark:text-gray-300 uppercase tracking-wider cursor-pointer hover:bg-gray-100 dark:hover:bg-slate-600"
+                    hx-get="/api/seismo-dashboard/units?sort=location&order={{ next_order }}&search={{ search }}&status={{ status }}&modem={{ modem }}"
+                    hx-target="#seismo-units-list"
+                    hx-swap="innerHTML">
+                    <span class="flex items-center gap-1">
+                        Location
+                        {% if sort == 'location' %}
+                        <svg class="w-4 h-4 {% if order == 'desc' %}rotate-180{% endif %}" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                            <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M5 15l7-7 7 7"></path>
+                        </svg>
+                        {% endif %}
+                    </span>
+                </th>
+                {% set next_order = 'desc' if (sort == 'last_calibrated' and order == 'asc') else 'asc' %}
+                <th class="px-4 py-3 text-left text-xs font-medium text-gray-700 dark:text-gray-300 uppercase tracking-wider cursor-pointer hover:bg-gray-100 dark:hover:bg-slate-600"
+                    hx-get="/api/seismo-dashboard/units?sort=last_calibrated&order={{ next_order }}&search={{ search }}&status={{ status }}&modem={{ modem }}"
+                    hx-target="#seismo-units-list"
+                    hx-swap="innerHTML">
+                    <span class="flex items-center gap-1">
+                        Last Calibrated
+                        {% if sort == 'last_calibrated' %}
+                        <svg class="w-4 h-4 {% if order == 'desc' %}rotate-180{% endif %}" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                            <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M5 15l7-7 7 7"></path>
+                        </svg>
+                        {% endif %}
+                    </span>
+                </th>
+                {% set next_order = 'desc' if (sort == 'notes' and order == 'asc') else 'asc' %}
+                <th class="px-4 py-3 text-left text-xs font-medium text-gray-700 dark:text-gray-300 uppercase tracking-wider cursor-pointer hover:bg-gray-100 dark:hover:bg-slate-600"
+                    hx-get="/api/seismo-dashboard/units?sort=notes&order={{ next_order }}&search={{ search }}&status={{ status }}&modem={{ modem }}"
+                    hx-target="#seismo-units-list"
+                    hx-swap="innerHTML">
+                    <span class="flex items-center gap-1">
+                        Notes
+                        {% if sort == 'notes' %}
+                        <svg class="w-4 h-4 {% if order == 'desc' %}rotate-180{% endif %}" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                            <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M5 15l7-7 7 7"></path>
+                        </svg>
+                        {% endif %}
+                    </span>
+                </th>
                 <th class="px-4 py-3 text-right text-xs font-medium text-gray-700 dark:text-gray-300 uppercase tracking-wider">Actions</th>
             </tr>
         </thead>
@@ -54,6 +133,27 @@
                     <span class="text-gray-400 dark:text-gray-600">—</span>
                     {% endif %}
                 </td>
+                <td class="px-4 py-3 whitespace-nowrap text-sm text-gray-900 dark:text-gray-300">
+                    {% if unit.last_calibrated %}
+                    <span class="inline-flex items-center gap-1.5">
+                        {% if unit.next_calibration_due and today %}
+                            {% set days_until = (unit.next_calibration_due - today).days %}
+                            {% if days_until < 0 %}
+                            <span class="w-2 h-2 rounded-full bg-red-500" title="Calibration expired {{ -days_until }} days ago"></span>
+                            {% elif days_until <= 14 %}
+                            <span class="w-2 h-2 rounded-full bg-yellow-500" title="Calibration expires in {{ days_until }} days"></span>
+                            {% else %}
+                            <span class="w-2 h-2 rounded-full bg-green-500" title="Calibration valid ({{ days_until }} days remaining)"></span>
+                            {% endif %}
+                        {% else %}
+                        <span class="w-2 h-2 rounded-full bg-gray-400" title="No expiry date set"></span>
+                        {% endif %}
+                        {{ unit.last_calibrated.strftime('%Y-%m-%d') }}
+                    </span>
+                    {% else %}
+                    <span class="text-gray-400 dark:text-gray-600">—</span>
+                    {% endif %}
+                </td>
                 <td class="px-4 py-3 text-sm text-gray-700 dark:text-gray-400">
                     {% if unit.note %}
                     <span class="truncate max-w-xs inline-block" title="{{ unit.note }}">{{ unit.note }}</span>
@@ -72,9 +172,12 @@
     </table>
 </div>
 
-{% if search %}
+{% if search or status or modem %}
 <div class="mt-4 text-sm text-gray-600 dark:text-gray-400">
-    Found {{ units|length }} seismograph(s) matching "{{ search }}"
+    Found {{ units|length }} seismograph(s)
+    {% if search %} matching "{{ search }}"{% endif %}
+    {% if status %} ({{ status }}){% endif %}
+    {% if modem %} ({{ 'with modem' if modem == 'with' else 'without modem' }}){% endif %}
 </div>
 {% endif %}
 
diff --git a/templates/roster.html b/templates/roster.html
index df989b7..5407c98 100644
--- a/templates/roster.html
+++ b/templates/roster.html
@@ -145,16 +145,12 @@
             <div id="seismographFields" class="space-y-4 border-t border-gray-200 dark:border-gray-700 pt-4">
                 <p class="text-sm font-semibold text-gray-700 dark:text-gray-300">Seismograph Information</p>
                 <div>
-                    <label class="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-2">Last Calibrated</label>
-                    <input type="date" name="last_calibrated"
+                    <label class="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-2">Date of Last Calibration</label>
+                    <input type="date" name="last_calibrated" id="addLastCalibrated"
                         class="w-full px-4 py-2 rounded-lg border border-gray-300 dark:border-gray-600 bg-white dark:bg-slate-700 text-gray-900 dark:text-white focus:ring-2 focus:ring-seismo-orange">
+                    <p class="text-xs text-gray-500 dark:text-gray-400 mt-1">Next calibration due date will be calculated automatically</p>
                 </div>
-                <div>
-                    <label class="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-2">Next Calibration Due</label>
-                    <input type="date" name="next_calibration_due"
-                        class="w-full px-4 py-2 rounded-lg border border-gray-300 dark:border-gray-600 bg-white dark:bg-slate-700 text-gray-900 dark:text-white focus:ring-2 focus:ring-seismo-orange">
-                    <p class="text-xs text-gray-500 dark:text-gray-400 mt-1">Typically 1 year after last calibration</p>
-                </div>
+                <input type="hidden" name="next_calibration_due" id="addNextCalibrationDue">
                 <div id="modemPairingField" class="hidden">
                     <label class="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-2">Deployed With Modem</label>
                     {% set picker_id = "-add-seismo" %}
@@ -325,15 +321,12 @@
             <div id="editSeismographFields" class="space-y-4 border-t border-gray-200 dark:border-gray-700 pt-4">
                 <p class="text-sm font-semibold text-gray-700 dark:text-gray-300">Seismograph Information</p>
                 <div>
-                    <label class="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-2">Last Calibrated</label>
+                    <label class="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-2">Date of Last Calibration</label>
                     <input type="date" name="last_calibrated" id="editLastCalibrated"
                         class="w-full px-4 py-2 rounded-lg border border-gray-300 dark:border-gray-600 bg-white dark:bg-slate-700 text-gray-900 dark:text-white focus:ring-2 focus:ring-seismo-orange">
+                    <p class="text-xs text-gray-500 dark:text-gray-400 mt-1">Next calibration due date will be calculated automatically</p>
                 </div>
-                <div>
-                    <label class="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-2">Next Calibration Due</label>
-                    <input type="date" name="next_calibration_due" id="editNextCalibrationDue"
-                        class="w-full px-4 py-2 rounded-lg border border-gray-300 dark:border-gray-600 bg-white dark:bg-slate-700 text-gray-900 dark:text-white focus:ring-2 focus:ring-seismo-orange">
-                </div>
+                <input type="hidden" name="next_calibration_due" id="editNextCalibrationDue">
                 <div id="editModemPairingField" class="hidden">
                     <label class="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-2">Deployed With Modem</label>
                     {% set picker_id = "-edit-seismo" %}
@@ -598,6 +591,58 @@
 </div>
 
 <script>
+    // Calibration interval in days (default 365, will be loaded from preferences)
+    let calibrationIntervalDays = 365;
+
+    // Load calibration interval from preferences
+    async function loadCalibrationInterval() {
+        try {
+            const response = await fetch('/api/settings/preferences');
+            if (response.ok) {
+                const prefs = await response.json();
+                calibrationIntervalDays = prefs.calibration_interval_days || 365;
+            }
+        } catch (e) {
+            console.error('Failed to load calibration interval:', e);
+        }
+    }
+
+    // Calculate next calibration due date from last calibrated date
+    function calculateNextCalibrationDue(lastCalibratedStr) {
+        if (!lastCalibratedStr) return '';
+        const lastCalibrated = new Date(lastCalibratedStr);
+        const nextDue = new Date(lastCalibrated);
+        nextDue.setDate(nextDue.getDate() + calibrationIntervalDays);
+        return nextDue.toISOString().split('T')[0];
+    }
+
+    // Setup auto-calculation for calibration fields
+    function setupCalibrationAutoCalc() {
+        // Add form
+        const addLastCal = document.getElementById('addLastCalibrated');
+        const addNextCal = document.getElementById('addNextCalibrationDue');
+        if (addLastCal && addNextCal) {
+            addLastCal.addEventListener('change', function() {
+                addNextCal.value = calculateNextCalibrationDue(this.value);
+            });
+        }
+
+        // Edit form
+        const editLastCal = document.getElementById('editLastCalibrated');
+        const editNextCal = document.getElementById('editNextCalibrationDue');
+        if (editLastCal && editNextCal) {
+            editLastCal.addEventListener('change', function() {
+                editNextCal.value = calculateNextCalibrationDue(this.value);
+            });
+        }
+    }
+
+    // Initialize on page load
+    document.addEventListener('DOMContentLoaded', function() {
+        loadCalibrationInterval();
+        setupCalibrationAutoCalc();
+    });
+
     // Add Unit Modal
     function openAddUnitModal() {
         document.getElementById('addUnitModal').classList.remove('hidden');
@@ -891,8 +936,11 @@
             document.getElementById('editRetiredCheckbox').checked = unit.retired;
 
             // Seismograph fields
-            document.getElementById('editLastCalibrated').value = unit.last_calibrated;
-            document.getElementById('editNextCalibrationDue').value = unit.next_calibration_due;
+            document.getElementById('editLastCalibrated').value = unit.last_calibrated || '';
+            // Calculate next calibration due from last calibrated
+            document.getElementById('editNextCalibrationDue').value = unit.last_calibrated
+                ? calculateNextCalibrationDue(unit.last_calibrated)
+                : '';
 
             // Populate modem picker for seismograph (uses -edit-seismo suffix)
             const modemPickerValue = document.getElementById('modem-picker-value-edit-seismo');
diff --git a/templates/seismographs.html b/templates/seismographs.html
index 7780b87..aa79abd 100644
--- a/templates/seismographs.html
+++ b/templates/seismographs.html
@@ -27,25 +27,50 @@
 
 <!-- Seismograph List -->
 <div class="rounded-xl shadow-lg bg-white dark:bg-slate-800 p-6">
-    <div class="mb-4 flex flex-col sm:flex-row sm:items-center sm:justify-between gap-4">
-        <h2 class="text-xl font-semibold text-gray-900 dark:text-white">All Seismographs</h2>
+    <div class="mb-4 flex flex-col gap-4">
+        <div class="flex flex-col sm:flex-row sm:items-center sm:justify-between gap-4">
+            <h2 class="text-xl font-semibold text-gray-900 dark:text-white">All Seismographs</h2>
 
-        <!-- Search Box -->
-        <div class="relative">
-            <input
-                type="text"
-                id="seismo-search"
-                placeholder="Search seismographs..."
-                class="w-full sm:w-64 px-4 py-2 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white focus:ring-2 focus:ring-blue-500 focus:border-transparent"
-                hx-get="/api/seismo-dashboard/units"
-                hx-trigger="keyup changed delay:300ms"
-                hx-target="#seismo-units-list"
-                hx-include="[name='search']"
-                name="search"
-            />
-            <svg class="absolute right-3 top-2.5 w-5 h-5 text-gray-400" fill="none" stroke="currentColor" viewBox="0 0 24 24">
-                <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M21 21l-6-6m2-5a7 7 0 11-14 0 7 7 0 0114 0z"></path>
-            </svg>
+            <!-- Search Box -->
+            <div class="relative">
+                <input
+                    type="text"
+                    id="seismo-search"
+                    placeholder="Search seismographs..."
+                    class="w-full sm:w-64 px-4 py-2 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white focus:ring-2 focus:ring-blue-500 focus:border-transparent"
+                    name="search"
+                />
+                <svg class="absolute right-3 top-2.5 w-5 h-5 text-gray-400" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                    <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M21 21l-6-6m2-5a7 7 0 11-14 0 7 7 0 0114 0z"></path>
+                </svg>
+            </div>
+        </div>
+
+        <!-- Filters -->
+        <div class="flex flex-wrap items-center gap-3">
+            <span class="text-sm text-gray-600 dark:text-gray-400">Filter:</span>
+
+            <!-- Status Filter -->
+            <select id="seismo-status-filter" name="status"
+                    class="px-3 py-1.5 text-sm border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white focus:ring-2 focus:ring-blue-500 focus:border-transparent">
+                <option value="">All Status</option>
+                <option value="deployed">Deployed</option>
+                <option value="benched">Benched</option>
+            </select>
+
+            <!-- Modem Filter -->
+            <select id="seismo-modem-filter" name="modem"
+                    class="px-3 py-1.5 text-sm border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white focus:ring-2 focus:ring-blue-500 focus:border-transparent">
+                <option value="">All Modems</option>
+                <option value="with">With Modem</option>
+                <option value="without">Without Modem</option>
+            </select>
+
+            <!-- Clear Filters Button -->
+            <button id="seismo-clear-filters" type="button"
+                    class="px-3 py-1.5 text-sm text-gray-600 dark:text-gray-400 hover:text-gray-900 dark:hover:text-white">
+                Clear Filters
+            </button>
         </div>
     </div>
 
@@ -59,17 +84,53 @@
 </div>
 
 <script>
-// Clear search input on escape key
 document.addEventListener('DOMContentLoaded', function() {
     const searchInput = document.getElementById('seismo-search');
-    if (searchInput) {
-        searchInput.addEventListener('keydown', function(e) {
-            if (e.key === 'Escape') {
-                this.value = '';
-                htmx.trigger(this, 'keyup');
-            }
-        });
+    const statusFilter = document.getElementById('seismo-status-filter');
+    const modemFilter = document.getElementById('seismo-modem-filter');
+    const clearBtn = document.getElementById('seismo-clear-filters');
+    const unitsList = document.getElementById('seismo-units-list');
+
+    // Build URL with current filter values
+    function buildUrl() {
+        const params = new URLSearchParams();
+        if (searchInput.value) params.set('search', searchInput.value);
+        if (statusFilter.value) params.set('status', statusFilter.value);
+        if (modemFilter.value) params.set('modem', modemFilter.value);
+        return '/api/seismo-dashboard/units' + (params.toString() ? '?' + params.toString() : '');
     }
+
+    // Trigger HTMX refresh
+    function refreshList() {
+        htmx.ajax('GET', buildUrl(), {target: '#seismo-units-list', swap: 'innerHTML'});
+    }
+
+    // Search input with debounce
+    let debounceTimer;
+    searchInput.addEventListener('input', function() {
+        clearTimeout(debounceTimer);
+        debounceTimer = setTimeout(refreshList, 300);
+    });
+
+    // Clear search on escape
+    searchInput.addEventListener('keydown', function(e) {
+        if (e.key === 'Escape') {
+            this.value = '';
+            refreshList();
+        }
+    });
+
+    // Filter changes
+    statusFilter.addEventListener('change', refreshList);
+    modemFilter.addEventListener('change', refreshList);
+
+    // Clear all filters
+    clearBtn.addEventListener('click', function() {
+        searchInput.value = '';
+        statusFilter.value = '';
+        modemFilter.value = '';
+        refreshList();
+    });
 });
 </script>
 
diff --git a/templates/unit_detail.html b/templates/unit_detail.html
index 92e4f80..2443f24 100644
--- a/templates/unit_detail.html
+++ b/templates/unit_detail.html
@@ -144,12 +144,12 @@
                 <h3 class="text-lg font-semibold text-gray-900 dark:text-white mb-4">Seismograph Information</h3>
                 <div class="grid grid-cols-1 md:grid-cols-2 gap-6">
                     <div>
-                        <label class="text-sm font-medium text-gray-500 dark:text-gray-400">Last Calibrated</label>
+                        <label class="text-sm font-medium text-gray-500 dark:text-gray-400">Date of Last Calibration</label>
                         <p id="viewLastCalibrated" class="mt-1 text-gray-900 dark:text-white font-medium">--</p>
                     </div>
                     <div>
                         <label class="text-sm font-medium text-gray-500 dark:text-gray-400">Next Calibration Due</label>
-                        <p id="viewNextCalibrationDue" class="mt-1 text-gray-900 dark:text-white font-medium">--</p>
+                        <p id="viewNextCalibrationDue" class="mt-1 text-gray-900 dark:text-white font-medium inline-flex items-center gap-2">--</p>
                     </div>
                     <div>
                         <label class="text-sm font-medium text-gray-500 dark:text-gray-400">Deployed With Modem</label>
@@ -378,15 +378,12 @@
                 <h3 class="text-lg font-semibold text-gray-900 dark:text-white">Seismograph Information</h3>
                 <div class="grid grid-cols-1 md:grid-cols-2 gap-6">
                     <div>
-                        <label class="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-2">Last Calibrated</label>
+                        <label class="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-2">Date of Last Calibration</label>
                         <input type="date" name="last_calibrated" id="lastCalibrated"
                             class="w-full px-4 py-2 rounded-lg border border-gray-300 dark:border-gray-600 bg-white dark:bg-slate-700 text-gray-900 dark:text-white focus:ring-2 focus:ring-seismo-orange">
+                        <p class="text-xs text-gray-500 dark:text-gray-400 mt-1">Next calibration due date will be calculated automatically</p>
                     </div>
-                    <div>
-                        <label class="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-2">Next Calibration Due</label>
-                        <input type="date" name="next_calibration_due" id="nextCalibrationDue"
-                            class="w-full px-4 py-2 rounded-lg border border-gray-300 dark:border-gray-600 bg-white dark:bg-slate-700 text-gray-900 dark:text-white focus:ring-2 focus:ring-seismo-orange">
-                    </div>
+                    <input type="hidden" name="next_calibration_due" id="nextCalibrationDue">
                     <div>
                         <label class="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-2">Deployed With Modem</label>
                         <div class="flex gap-2">
@@ -589,6 +586,42 @@ let currentSnapshot = null;
 let unitMap = null;
 let mapMarker = null;
 
+// Calibration interval in days (default 365, will be loaded from preferences)
+let calibrationIntervalDays = 365;
+
+// Load calibration interval from preferences
+async function loadCalibrationInterval() {
+    try {
+        const response = await fetch('/api/settings/preferences');
+        if (response.ok) {
+            const prefs = await response.json();
+            calibrationIntervalDays = prefs.calibration_interval_days || 365;
+        }
+    } catch (e) {
+        console.error('Failed to load calibration interval:', e);
+    }
+}
+
+// Calculate next calibration due date from last calibrated date
+function calculateNextCalibrationDue(lastCalibratedStr) {
+    if (!lastCalibratedStr) return '';
+    const lastCalibrated = new Date(lastCalibratedStr);
+    const nextDue = new Date(lastCalibrated);
+    nextDue.setDate(nextDue.getDate() + calibrationIntervalDays);
+    return nextDue.toISOString().split('T')[0];
+}
+
+// Setup auto-calculation for calibration fields
+function setupCalibrationAutoCalc() {
+    const lastCal = document.getElementById('lastCalibrated');
+    const nextCal = document.getElementById('nextCalibrationDue');
+    if (lastCal && nextCal) {
+        lastCal.addEventListener('change', function() {
+            nextCal.value = calculateNextCalibrationDue(this.value);
+        });
+    }
+}
+
 // Fetch project display name (combines project_number, client_name, name)
 async function fetchProjectDisplay(projectId) {
     if (!projectId) return '';
@@ -819,7 +852,28 @@ function populateViewMode() {
 
     // Seismograph fields
     document.getElementById('viewLastCalibrated').textContent = currentUnit.last_calibrated || '--';
-    document.getElementById('viewNextCalibrationDue').textContent = currentUnit.next_calibration_due || '--';
+
+    // Calculate next calibration due and show with status indicator
+    const nextCalDueEl = document.getElementById('viewNextCalibrationDue');
+    if (currentUnit.last_calibrated) {
+        const nextDue = calculateNextCalibrationDue(currentUnit.last_calibrated);
+        const today = new Date().toISOString().split('T')[0];
+        const daysUntil = Math.floor((new Date(nextDue) - new Date(today)) / (1000 * 60 * 60 * 24));
+
+        let dotColor = 'bg-green-500';
+        let tooltip = `Calibration valid (${daysUntil} days remaining)`;
+        if (daysUntil < 0) {
+            dotColor = 'bg-red-500';
+            tooltip = `Calibration expired ${-daysUntil} days ago`;
+        } else if (daysUntil <= 14) {
+            dotColor = 'bg-yellow-500';
+            tooltip = `Calibration expires in ${daysUntil} days`;
+        }
+
+        nextCalDueEl.innerHTML = `<span class="w-2 h-2 rounded-full ${dotColor}" title="${tooltip}"></span>${nextDue}`;
+    } else {
+        nextCalDueEl.textContent = '--';
+    }
 
     // Deployed with modem - show as clickable link
     const modemLink = document.getElementById('viewDeployedWithModemLink');
@@ -960,7 +1014,10 @@ function populateEditForm() {
 
     // Seismograph fields
     document.getElementById('lastCalibrated').value = currentUnit.last_calibrated || '';
-    document.getElementById('nextCalibrationDue').value = currentUnit.next_calibration_due || '';
+    // Calculate next calibration due from last calibrated
+    document.getElementById('nextCalibrationDue').value = currentUnit.last_calibrated
+        ? calculateNextCalibrationDue(currentUnit.last_calibrated)
+        : '';
 
     // Populate modem picker for seismograph (uses -detail-seismo suffix)
     const modemPickerValue = document.getElementById('modem-picker-value-detail-seismo');
@@ -1535,6 +1592,8 @@ async function pingModem() {
 }
 
 // Load data when page loads
+loadCalibrationInterval();
+setupCalibrationAutoCalc();
 loadUnitData().then(() => {
     loadPhotos();
     loadUnitHistory();