diff --git a/packages/flutter/lib/src/material/constants.dart b/packages/flutter/lib/src/material/constants.dart
index 5c175006d6..526add3591 100644
--- a/packages/flutter/lib/src/material/constants.dart
+++ b/packages/flutter/lib/src/material/constants.dart
@@ -17,13 +17,13 @@ const double kTextTabBarHeight = 48.0;
 const Duration kThemeChangeDuration = const Duration(milliseconds: 200);
 
 /// The radius of a circular material ink response in logical pixels.
-const double kRadialReactionRadius = 24.0;
+const double kRadialReactionRadius = 20.0;
 
 /// The amount of time a circular material ink response should take to expand to its full size.
-const Duration kRadialReactionDuration = const Duration(milliseconds: 200);
+const Duration kRadialReactionDuration = const Duration(milliseconds: 100);
 
 /// The value of the alpha channel to use when drawing a circular material ink response.
-const int kRadialReactionAlpha = 0x33;
+const int kRadialReactionAlpha = 0x1F;
 
 /// The duration of the horizontal scroll animation that occurs when a tab is tapped.
 const Duration kTabScrollDuration = const Duration(milliseconds: 300);
diff --git a/packages/flutter/lib/src/material/radio.dart b/packages/flutter/lib/src/material/radio.dart
index 29539a52b9..422a82a82f 100644
--- a/packages/flutter/lib/src/material/radio.dart
+++ b/packages/flutter/lib/src/material/radio.dart
@@ -11,9 +11,8 @@ import 'debug.dart';
 import 'theme.dart';
 import 'toggleable.dart';
 
-const double _kDiameter = 16.0;
-const double _kOuterRadius = _kDiameter / 2.0;
-const double _kInnerRadius = 5.0;
+const double _kOuterRadius = 8.0;
+const double _kInnerRadius = 4.5;
 
 /// A material design radio button.
 ///