Board-feet to gallons (US dry) conversion calculator shown above calculates how many gallons (US dry) are in 'X' board-feet (where 'X' is the number of board-feet to convert to gallons (US dry)). In order to convert a value from board-feet to gallons (US dry) (from fbm to gal) just type the number of fbm to be converted to gal and then click on the 'convert' button.