Revenue and cost of goods sold—gross profit and margin % of revenue.
Gross profit = revenue − cost; margin % = (gross profit ÷ revenue) × 100 when revenue > 0. Revenue must be positive; cost may be zero (100% margin) but not negative in validation.
This calculator uses plain decimal numbers. If a result looks wrong, check whether you used a comma instead of a dot (or vice versa) where the field expects one.