Android: How to change the Size of the RadioButton

It can be done but is not as simple as setting the Layout_Width and Layout_height as with EditTexts, Buttons etc. To modify the size/looks of a view like a checkbox/radio button use the "Background" and "Button" properties to specify your own drawables.

This is an older page, and the locations are different now, but this'll give you an idea : http://www.anddev.org/tutorial_change_look_of_checkbox-t4553.html

you can use scalex and scaley properties , then use translationX and translationY to put it in the radiobutton windows.

<RadioButton
            android:id="@+id/rbtnfkilo"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:scaleX="1.4"
            android:scaleY="1.4"
            android:text="Kilogram"
            android:textColor="#fff"
            android:textSize="18sp"
            android:translationX="24dp" />

One quick hacky solution is to scale the button down:

<RadioButton
  android:scaleX="0.5"
  android:scaleY="0.5" />

This works great for going smaller.

For going larger, this tends to cause some clipping from the container View, so you'll likely have to hardcode the height/width of the RadioGroup to fit the scaled buttons. The button drawable can also get noticeably pixelated the larger you go, so it's not really great if you want something 3x larger...