Adjust icon size of Floating action button (fab)

Question

The new floating action button should be 56dp x 56dp and the icon inside it should

Answer 1

There are three key XML attributes for custom FABs:

• app:fabSize: Either "mini" (40dp), "normal"(56dp)(default) or "auto"
• app:fabCustomSize: This will decide the overall FAB size.
• app:maxImageSize: This will decide the icon size.

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Example:

app:fabCustomSize="64dp" 
app:maxImageSize="32dp"

The FAB padding (the space between the icon and the background circle, aka ripple) is calculated implicitly by:

4-edge padding = (fabCustomSize - maxImageSize) / 2.0 = 16

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Note that the margins of the fab can be set by the usual android:margin xml tag properties.