diff --git a/packages/mui-joy/src/Radio/Radio.tsx b/packages/mui-joy/src/Radio/Radio.tsx
index 56e986738383a1..c92f3933aaf353 100644
--- a/packages/mui-joy/src/Radio/Radio.tsx
+++ b/packages/mui-joy/src/Radio/Radio.tsx
@@ -205,8 +205,8 @@ const RadioIcon = styled('span', {
   slot: 'Icon',
   overridesResolver: (props, styles) => styles.icon,
 })<{ ownerState: RadioOwnerState }>(({ ownerState }) => ({
-  width: '50%',
-  height: '50%',
+  width: 'calc(var(--Radio-size) / 2)',
+  height: 'calc(var(--Radio-size) / 2)',
   borderRadius: 'inherit',
   color: 'inherit',
   backgroundColor: 'currentColor',