how do i add per gallon price on square

[highcountryrvpa]

i sell propane per gallon and want to know if square can add up price?

[VanKalkerFarms]

Selling items by weight or gallons aren't something set up directly in Square yet.  the easiest thing to do would be to have the Propane item be a variably priced item and you would just enter the total value of that item when you chose it.