diff --git a/server/src/wled_controller/static/js/features/calibration.js b/server/src/wled_controller/static/js/features/calibration.js
index 199be5c..de84330 100644
--- a/server/src/wled_controller/static/js/features/calibration.js
+++ b/server/src/wled_controller/static/js/features/calibration.js
@@ -214,6 +214,20 @@ export async function showCSSCalibration(cssId) {
         const testGroup = document.getElementById('calibration-css-test-group');
         testGroup.style.display = devices.length ? '' : 'none';
 
+        // Pre-select device: 1) LED count match, 2) last remembered, 3) first
+        if (devices.length) {
+            const rememberedId = localStorage.getItem('css_calibration_test_device');
+            let selected = null;
+            if (source.led_count > 0) {
+                selected = devices.find(d => d.led_count === source.led_count) || null;
+            }
+            if (!selected && rememberedId) {
+                selected = devices.find(d => d.id === rememberedId) || null;
+            }
+            if (selected) testDeviceSelect.value = selected.id;
+            testDeviceSelect.onchange = () => localStorage.setItem('css_calibration_test_device', testDeviceSelect.value);
+        }
+
         // Populate calibration fields
         const preview = document.querySelector('.calibration-preview');
         preview.style.aspectRatio = '';