diff --git a/api/app.py b/api/app.py
index 318de3f..8aa6b19 100644
--- a/api/app.py
+++ b/api/app.py
@@ -25,6 +25,9 @@ from logging.handlers import RotatingFileHandler
 import uuid
 import contextvars
 
+# Track API start time for uptime calculation
+API_START_TIME = time.time()
+
 from network_manager import NetworkManager
 from wireguard_manager import WireGuardManager
 from peer_registry import PeerRegistry
@@ -305,10 +308,14 @@ def get_cell_status():
         
         peers = peer_registry.list_peers()
         
+        # Calculate actual uptime
+        current_time = time.time()
+        uptime_seconds = int(current_time - API_START_TIME)
+        
         return jsonify({
             "cell_name": "personal-internet-cell",
             "domain": "cell.local",
-            "uptime": 3600,  # Placeholder
+            "uptime": uptime_seconds,
             "peers_count": len(peers),
             "services": services_status,
             "timestamp": datetime.utcnow().isoformat()
diff --git a/webui/src/pages/Dashboard.jsx b/webui/src/pages/Dashboard.jsx
index a5fa83a..16cf79f 100644
--- a/webui/src/pages/Dashboard.jsx
+++ b/webui/src/pages/Dashboard.jsx
@@ -62,6 +62,23 @@ function Dashboard({ isOnline }) {
     }
   };
 
+  const formatUptime = (seconds) => {
+    if (!seconds || seconds < 0) return '0s';
+    
+    const days = Math.floor(seconds / 86400);
+    const hours = Math.floor((seconds % 86400) / 3600);
+    const minutes = Math.floor((seconds % 3600) / 60);
+    const secs = Math.floor(seconds % 60);
+    
+    const parts = [];
+    if (days > 0) parts.push(`${days}d`);
+    if (hours > 0) parts.push(`${hours}h`);
+    if (minutes > 0) parts.push(`${minutes}m`);
+    if (secs > 0 || parts.length === 0) parts.push(`${secs}s`);
+    
+    return parts.join(' ');
+  };
+
   const handleServiceControl = async (serviceName, action) => {
     if (!isOnline) return;
     
@@ -224,7 +241,7 @@ function Dashboard({ isOnline }) {
                 <div className="ml-4">
                   <p className="text-sm font-medium text-gray-500">Uptime</p>
                   <p className="text-lg font-semibold text-gray-900">
-                    {Math.floor((cellStatus.uptime || 0) / 3600)}h {Math.floor(((cellStatus.uptime || 0) % 3600) / 60)}m
+                    {formatUptime(cellStatus.uptime || 0)}
                   </p>
                 </div>
               </div>