fabRadius property

Border radius value for FloatingActionButton.

If not defined and defaultRadius is undefined, defaults to kFabRadius 16dp, based on M3 Specification for normal sized FAB. https://m3.material.io/components/floating-action-button/specs

The border radius is only assigned when fabUseShape is true, if fabUseShape is false, the fabRadius or fabAlwaysCircular has no effect on FAB shapes.

If fabAlwaysCircular is true and a radius is given by defaultRadius or fabRadius the FAB will still be circular, radius settings have no effect then.

If ThemeData.useMaterial3 and fabUseShape are true, you cannot define FAB buttons that get the same rounding style as defined by the M3 spec. This is because the FAB cannot be themed in same style as its default null shape behavior. See issue #107946 for more information.