diff --git a/frontend/src/App.tsx b/frontend/src/App.tsx
index 6460b3f..78b7341 100644
--- a/frontend/src/App.tsx
+++ b/frontend/src/App.tsx
@@ -380,6 +380,7 @@ export default function App() {
                   visible={heatmapVisible}
                   opacity={settings.heatmapOpacity}
                   radiusMeters={settings.heatmapRadius}
+                  rsrpThreshold={settings.rsrpThreshold}
                 />
                 <CoverageBoundary
                   points={coverageResult.points}
diff --git a/frontend/src/components/map/GeographicHeatmap.tsx b/frontend/src/components/map/GeographicHeatmap.tsx
index 0419785..0faba07 100644
--- a/frontend/src/components/map/GeographicHeatmap.tsx
+++ b/frontend/src/components/map/GeographicHeatmap.tsx
@@ -24,6 +24,7 @@ interface GeographicHeatmapProps {
   visible: boolean;
   opacity?: number;
   radiusMeters?: number;
+  rsrpThreshold?: number;
 }
 
 export default function GeographicHeatmap({
@@ -31,6 +32,7 @@ export default function GeographicHeatmap({
   visible,
   opacity = 0.7,
   radiusMeters = 400,
+  rsrpThreshold = -100,
 }: GeographicHeatmapProps) {
   const map = useMap();
   const layerRef = useRef<L.GridLayer | null>(null);
@@ -53,7 +55,12 @@ export default function GeographicHeatmap({
     rendererRef.current.setRadiusMeters(radiusMeters);
   }, [radiusMeters]);
 
-  // Invalidate cache when points change (use length + first/last coords as fingerprint)
+  // Update renderer threshold when prop changes
+  useEffect(() => {
+    rendererRef.current.setRsrpThreshold(rsrpThreshold);
+  }, [rsrpThreshold]);
+
+  // Invalidate cache when points or threshold change
   useEffect(() => {
     if (points.length === 0) {
       rendererRef.current.setPointsHash('empty');
@@ -61,9 +68,9 @@ export default function GeographicHeatmap({
     }
     const first = points[0];
     const last = points[points.length - 1];
-    const hash = `${points.length}:${first.lat.toFixed(4)},${first.lon.toFixed(4)}:${last.rsrp}`;
+    const hash = `${points.length}:${first.lat.toFixed(4)},${first.lon.toFixed(4)}:${last.rsrp}:t${rsrpThreshold}`;
     rendererRef.current.setPointsHash(hash);
-  }, [points]);
+  }, [points, rsrpThreshold]);
 
   // Create / destroy GridLayer
   const createLayer = useCallback(() => {
diff --git a/frontend/src/components/map/HeatmapTileRenderer.ts b/frontend/src/components/map/HeatmapTileRenderer.ts
index f66d1d6..f3453d2 100644
--- a/frontend/src/components/map/HeatmapTileRenderer.ts
+++ b/frontend/src/components/map/HeatmapTileRenderer.ts
@@ -34,6 +34,7 @@ export interface HeatmapPoint {
 export class HeatmapTileRenderer {
   private tileSize = 256;
   private radiusMeters: number;
+  private rsrpThreshold: number;
 
   // LRU cache: key → canvas
   private cache = new Map<string, ImageData>();
@@ -42,9 +43,10 @@ export class HeatmapTileRenderer {
   // Points fingerprint for cache invalidation
   private pointsHash = '';
 
-  constructor(radiusMeters = 400, maxCacheSize = 150) {
+  constructor(radiusMeters = 400, maxCacheSize = 150, rsrpThreshold = -100) {
     this.radiusMeters = radiusMeters;
     this.maxCacheSize = maxCacheSize;
+    this.rsrpThreshold = rsrpThreshold;
   }
 
   /** Update the geographic radius of each coverage point. */
@@ -55,6 +57,14 @@ export class HeatmapTileRenderer {
     }
   }
 
+  /** Update the RSRP threshold — points below this are not rendered. */
+  setRsrpThreshold(threshold: number): void {
+    if (threshold !== this.rsrpThreshold) {
+      this.rsrpThreshold = threshold;
+      this.clearCache();
+    }
+  }
+
   /** Call when points change to invalidate cache. */
   setPointsHash(hash: string): void {
     if (hash !== this.pointsHash) {
@@ -105,9 +115,10 @@ export class HeatmapTileRenderer {
     // still contribute their gaussian tail inside the tile
     const bufferDeg = (this.radiusMeters / 111_000) * 2;
 
-    // Filter relevant points
+    // Filter relevant points — geographic bounds AND RSRP threshold
     const relevant = points.filter(
       (p) =>
+        p.rsrp >= this.rsrpThreshold &&
         p.lat >= latMin - bufferDeg &&
         p.lat <= latMax + bufferDeg &&
         p.lon >= lonMin - bufferDeg &&