Gallons (UK) to cups (metric) conversion calculator above calculates how many cups (metric) are in 'X' gallons (UK) (where 'X' is the number of gallons (UK) to convert to cups (metric)). In order to convert a value from gallons (UK) to cups (metric) simply type the number of gal to be converted to cups (metric) and then click on the 'convert' button.