diff --git a/apps/nowcasting-app/components/map/sitesMap.tsx b/apps/nowcasting-app/components/map/sitesMap.tsx
index 9ab90249..0056101f 100644
--- a/apps/nowcasting-app/components/map/sitesMap.tsx
+++ b/apps/nowcasting-app/components/map/sitesMap.tsx
@@ -25,6 +25,7 @@ import { theme } from "../../tailwind.config";
 import { Feature, FeatureCollection } from "geojson";
 import Slider from "./sitesMapFeatures/sitesZoomSlider";
 import SitesLegend from "./sitesMapFeatures/sitesLegend";
+import { getRingMultiplier } from "./sitesMapFeatures/utils";
 import { safelyUpdateMapData } from "../helpers/mapUtils";
 
 const yellow = theme.extend.colors["ocf-yellow"].DEFAULT;
@@ -100,20 +101,6 @@ const SitesMap: React.FC<SitesMapProps> = ({
     1
   ];
 
-  const getRingMultiplier = (aggregationLevel: AGGREGATION_LEVELS) => {
-    // TODO: this will need to be dynamic depending on user's site capacities
-    switch (aggregationLevel) {
-      case AGGREGATION_LEVELS.SITE:
-        return 10;
-      case AGGREGATION_LEVELS.GSP:
-        return 5;
-      case AGGREGATION_LEVELS.REGION:
-        return 1.5;
-      case AGGREGATION_LEVELS.NATIONAL:
-        return 0.3;
-    }
-  };
-
   const generateGeoJsonForecastData: (
     forecastData?: FcAllResData,
     targetTime?: string
@@ -282,6 +269,11 @@ const SitesMap: React.FC<SitesMapProps> = ({
       addGroupSource(map, groupName, groupFeatureArray);
     }
 
+    // get the maximum capacity in all the FeatureArrays, but feature.properties might be null, if so us 1
+    const maxCapacity = Math.max(
+      ...groupFeatureArray.map((feature) => feature.properties?.capacity || 1)
+    );
+
     if (groupName === "regions") {
       let dnoBoundariesSource = map.getSource("dnoBoundaries") as unknown as
         | mapboxgl.GeoJSONSource
@@ -346,7 +338,7 @@ const SitesMap: React.FC<SitesMapProps> = ({
       map.setPaintProperty(`Capacity-${groupName}`, "circle-radius", [
         "*",
         ["to-number", ["get", "capacity"]],
-        getRingMultiplier(groupAggregationLevel)
+        getRingMultiplier(groupAggregationLevel, maxCapacity)
       ]);
       // const visibility = currentAggregationLevel === groupAggregationLevel ? "visible" : "none";
       const visibility = "visible";
@@ -366,7 +358,7 @@ const SitesMap: React.FC<SitesMapProps> = ({
           "circle-radius": [
             "*",
             ["to-number", ["get", "capacity"]],
-            getRingMultiplier(groupAggregationLevel)
+            getRingMultiplier(groupAggregationLevel, maxCapacity)
           ],
           "circle-stroke-color": [
             "case",
@@ -412,7 +404,7 @@ const SitesMap: React.FC<SitesMapProps> = ({
       map.setPaintProperty(`Generation-${groupName}`, "circle-radius", [
         "*",
         ["to-number", ["get", "expectedPVRadius"]],
-        getRingMultiplier(groupAggregationLevel)
+        getRingMultiplier(groupAggregationLevel, maxCapacity)
       ]);
       // const visibility = currentAggregationLevel === groupAggregationLevel ? "visible" : "none";
       const visibility = "visible";
@@ -432,7 +424,7 @@ const SitesMap: React.FC<SitesMapProps> = ({
           "circle-radius": [
             "*",
             ["to-number", ["get", "expectedPVRadius"]],
-            getRingMultiplier(groupAggregationLevel)
+            getRingMultiplier(groupAggregationLevel, maxCapacity)
           ],
           "circle-color": [
             "case",
diff --git a/apps/nowcasting-app/components/map/sitesMapFeatures/utils.test.tsx b/apps/nowcasting-app/components/map/sitesMapFeatures/utils.test.tsx
new file mode 100644
index 00000000..e0a82fd5
--- /dev/null
+++ b/apps/nowcasting-app/components/map/sitesMapFeatures/utils.test.tsx
@@ -0,0 +1,16 @@
+import { describe, expect, test } from "@jest/globals";
+import { getRingMultiplier } from "./utils";
+import { AGGREGATION_LEVELS } from "../../../constant";
+
+describe("Check getRingMultiplier", () => {
+  test("check getRingMultiplier works for different values", () => {
+    expect(getRingMultiplier(AGGREGATION_LEVELS.SITE, 10)).toBe(3);
+    expect(getRingMultiplier(AGGREGATION_LEVELS.GSP, 10)).toBe(4.5);
+    expect(getRingMultiplier(AGGREGATION_LEVELS.REGION, 10)).toBe(6);
+    expect(getRingMultiplier(AGGREGATION_LEVELS.NATIONAL, 10)).toBe(10);
+    expect(getRingMultiplier(AGGREGATION_LEVELS.SITE, 20)).toBe(1.5);
+    expect(getRingMultiplier(AGGREGATION_LEVELS.GSP, 20)).toBe(2.25);
+    expect(getRingMultiplier(AGGREGATION_LEVELS.REGION, 20)).toBe(3);
+    expect(getRingMultiplier(AGGREGATION_LEVELS.NATIONAL, 20)).toBe(5);
+  });
+});
diff --git a/apps/nowcasting-app/components/map/sitesMapFeatures/utils.tsx b/apps/nowcasting-app/components/map/sitesMapFeatures/utils.tsx
new file mode 100644
index 00000000..b0f430df
--- /dev/null
+++ b/apps/nowcasting-app/components/map/sitesMapFeatures/utils.tsx
@@ -0,0 +1,19 @@
+import { AGGREGATION_LEVELS } from "../../../constant";
+
+export const getRingMultiplier = (aggregationLevel: AGGREGATION_LEVELS, maxCapacity: number) => {
+  // Get the circle multiplier based, which will times the Expected PV value to get the radius
+  // We used to use 0.3 for National, 1.5 for DNO, 5 for GSP and 10 for Sites.
+  // Now we use a multiplier based on the max capacity of the the different sites/regions.
+  // If a client has 100 3 KW sites. Then the National multipler will be about 0.3.
+
+  switch (aggregationLevel) {
+    case AGGREGATION_LEVELS.SITE:
+      return 30 / maxCapacity;
+    case AGGREGATION_LEVELS.GSP:
+      return 45 / maxCapacity;
+    case AGGREGATION_LEVELS.REGION:
+      return 60 / maxCapacity;
+    case AGGREGATION_LEVELS.NATIONAL:
+      return 100 / maxCapacity;
+  }
+};