WE sell items by the pound at Farmers' markets. So I would like to do the calculation in the Square app by the item (3.3 lbs spare ribs X $5/lbs =$15.15) + .(95 lbs pork chops X $6.50/lbs=$6.18) = $21.33 then CHARGE
When you create an item you can select if the item is by unit or by weight. once you create that item by weight and assign it a price per pound and choose it at checkout Square will ask for the amount of weight being sold when you sell that item.
