What is GP?
Gross profit is what's left from a sale after paying for what went into it: the coffee, milk, cake or bread, and the cup or bag it goes out in. It's usually shown as a percentage of the price, so you can compare a £3.40 flat white with a £7.50 toastie.
GP % = (price without VAT − cost to make) ÷ price without VAT
It leaves out wages, rent and energy, which are paid from your gross profit. That's why GP needs to be high: a cafe usually needs around 65 to 75% across the menu to cover those and still make money.