Identify the market price per unit
Identify the supply curve or marginal cost curve
Find the quantity sold at the market price
Determine the area above the supply curve and below the market price up to the sold quantity
Calculate producer surplus as the total area of that region
For a linear supply curve, use the triangle formula: 1/2 × base × height
Base = quantity sold
Height = market price minus the supply curve price at zero quantity
For a stepwise or discrete supply schedule, add the differences between market price and each seller’s minimum acceptable price for all units sold