Bohr radius to femtometers converter above calculates how many femtometers are in 'X' Bohr radius (where 'X' is the number of Bohr radius to convert to femtometers). In order to convert a value from Bohr radius to femtometers (from a0 to fm) just type the number of a0 to be converted to fm and then click on the 'convert' button.