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