diff --git a/apps/web/src/utils/sparkline.ts b/apps/web/src/utils/sparkline.ts
index bec8386..17e72ea 100644
--- a/apps/web/src/utils/sparkline.ts
+++ b/apps/web/src/utils/sparkline.ts
@@ -1,4 +1,4 @@
-export function sparkline(values: number[], width = 120, height = 32, color = '#60a5fa'): string {
+export function sparkline(values: number[], width = 120, height = 32, color = '#60a5fa', region = '__none__'): string {
   if (!values.length) return '';
   const max = Math.max(...values, 1);
   const min = Math.min(...values, 0);
@@ -9,7 +9,7 @@ export function sparkline(values: number[], width = 120, height = 32, color = '#
     const y = height - ((v - min) / range) * (height - 4) - 2;
     return `${x},${y}`;
   }).join(' ');
-  return `<svg width="${width}" height="${height}" class="inline-block" data-vals="${values.join(',')}"><polyline points="${points}" fill="none" stroke="${color}" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"/></svg>`;
+  return `<svg width="${width}" height="${height}" class="inline-block" data-vals="${values.join(',')}" data-region="${region}"><polyline points="${points}" fill="none" stroke="${color}" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"/></svg>`;
 }
 
 // Given pings with region+latency, pick the region with the lowest avg latency
@@ -42,5 +42,5 @@ export function sparklineFromPings(pings: Array<{latency_ms?: number|null, regio
   }
 
   const color = COLORS[bestRegion] || '#60a5fa';
-  return sparkline(byRegion[bestRegion], width, height, color);
+  return sparkline(byRegion[bestRegion], width, height, color, bestRegion);
 }
diff --git a/apps/web/src/views/home.ejs b/apps/web/src/views/home.ejs
index a73842e..bc549bd 100644
--- a/apps/web/src/views/home.ejs
+++ b/apps/web/src/views/home.ejs
@@ -76,6 +76,50 @@
       } catch {}
     }, 30000);
 
+    const REGION_COLORS = {
+      'eu-central': '#3b82f6',
+      'us-east': '#10b981',
+      'us-west': '#f59e0b',
+      'ap-southeast': '#a78bfa',
+    };
+
+    // Per-monitor, per-region latency tracking for sparkline (mirrors SSR sparklineFromPings)
+    const sparkData = {};
+    // Seed from SSR data-vals and data-region
+    document.querySelectorAll('[data-monitor-id]').forEach(card => {
+      const mid = card.dataset.monitorId;
+      const svg = card.querySelector('.stat-sparkline svg');
+      if (!svg) return;
+      const region = svg.dataset.region || '__none__';
+      const vals = svg.dataset.vals ? svg.dataset.vals.split(',').map(Number) : [];
+      sparkData[mid] = {};
+      sparkData[mid][region] = vals;
+    });
+
+    function redrawSparkline(card, monitorId) {
+      const regions = sparkData[monitorId] || {};
+      // Pick region with lowest average latency (same as SSR)
+      let bestRegion = '__none__', bestAvg = Infinity;
+      for (const [region, vals] of Object.entries(regions)) {
+        if (!vals.length) continue;
+        const avg = vals.reduce((a, b) => a + b, 0) / vals.length;
+        if (avg < bestAvg) { bestAvg = avg; bestRegion = region; }
+      }
+      const vals = regions[bestRegion];
+      if (!vals || !vals.length) return;
+      const color = REGION_COLORS[bestRegion] || '#60a5fa';
+      const W = 120, H = 32;
+      const max = Math.max(...vals, 1);
+      const min = Math.min(...vals, 0);
+      const range = max - min || 1;
+      const step = W / Math.max(vals.length - 1, 1);
+      const points = vals.map((v, i) => `${i * step},${H - ((v - min) / range) * (H - 4) - 2}`).join(' ');
+      const sparkEl = card.querySelector('.stat-sparkline');
+      if (sparkEl) {
+        sparkEl.innerHTML = `<svg width="${W}" height="${H}" class="inline-block" data-vals="${vals.join(',')}" data-region="${bestRegion}"><polyline points="${points}" fill="none" stroke="${color}" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"/></svg>`;
+      }
+    }
+
     // SSE: on each ping, update text fields and redraw sparkline in place
     watchAccount((ping) => {
       const card = document.querySelector(`[data-monitor-id="${ping.monitor_id}"]`);
@@ -89,30 +133,15 @@
       if (ping.latency_ms != null) card.querySelector('.stat-latency').textContent = ping.latency_ms + 'ms';
       card.querySelector('.stat-last').innerHTML = timeAgo(ping.checked_at);
 
-      // Sparkline — append point to existing polyline, drop oldest, no refetch
+      // Update sparkline data per region, then redraw picking best region
       if (ping.latency_ms != null) {
-        const sparkEl = card.querySelector('.stat-sparkline');
-        const polyline = sparkEl?.querySelector('polyline');
-        if (polyline) {
-          const pts = polyline.getAttribute('points').trim().split(' ').filter(Boolean);
-          const W = 120, H = 32;
-          // Parse existing points
-          let coords = pts.map(p => p.split(',').map(Number));
-          // Extract just y-values (latencies are encoded in y relative to scale)
-          // Easier: maintain a data attr on the svg with the raw values
-          const svg = sparkEl.querySelector('svg');
-          let vals = svg?.dataset.vals ? svg.dataset.vals.split(',').map(Number) : [];
-          vals.push(ping.latency_ms);
-          if (vals.length > 20) vals.shift();
-          if (svg) svg.dataset.vals = vals.join(',');
-          // Redraw polyline in place
-          const max = Math.max(...vals, 1);
-          const min = Math.min(...vals, 0);
-          const range = max - min || 1;
-          const step = W / Math.max(vals.length - 1, 1);
-          const newPts = vals.map((v, i) => `${i * step},${H - ((v - min) / range) * (H - 4) - 2}`).join(' ');
-          polyline.setAttribute('points', newPts);
-        }
+        const mid = ping.monitor_id;
+        const region = ping.region || '__none__';
+        if (!sparkData[mid]) sparkData[mid] = {};
+        if (!sparkData[mid][region]) sparkData[mid][region] = [];
+        sparkData[mid][region].push(ping.latency_ms);
+        if (sparkData[mid][region].length > 20) sparkData[mid][region].shift();
+        redrawSparkline(card, mid);
       }
     });
   </script>