Gallons (US liquid) to milliliters converter on this page calculates how many milliliters are in 'X' gallons (US liquid) (where 'X' is the number of gallons (US liquid) to convert to milliliters). In order to convert a value from gallons (US liquid) to milliliters (from gal to mL) just type the number of gal to be converted to mL and then click on the 'convert' button.