Gallons (US liquid) to fluid ounces (US) conversion calculator above calculates how many fluid ounces (US) are in 'X' gallons (US liquid) (where 'X' is the number of gallons (US liquid) to convert to fluid ounces (US)). In order to convert a value from gallons (US liquid) to fluid ounces (US) (from gal to fl oz) just type the number of gal to be converted to fl oz and then click on the 'convert' button.