Producer Surplus Formula
Producer surplus = ½ × Q × (P_market - P_min).
Measure the economic benefit sellers gain when they receive more than their minimum acceptable price.
The Formula
Producer surplus is the economic benefit received by sellers who would have been willing to sell at a lower price than the market price. It equals the area of the triangle above the supply curve and below the market price line.
P_min is the minimum price at which any seller will supply (the supply curve intercept — essentially the marginal cost of the first unit), P_market is the actual market price, and Q is the quantity sold.
Producer surplus is closely related to profit but not identical. Profit subtracts all fixed and variable costs. Producer surplus measures the excess of revenue over the minimum sellers would accept (their variable cost / marginal cost).
Total welfare (social surplus) = Consumer Surplus + Producer Surplus. A competitive market maximizes total welfare. Monopolies shift surplus from consumers to producers while creating deadweight loss — transactions that would benefit both parties do not occur.
Subsidies to producers increase producer surplus and may reduce prices for consumers. Export taxes reduce producer surplus by lowering the domestic price sellers receive. Trade liberalization typically raises producer surplus in exporting countries while reducing it in import-competing industries.
Variables
| Symbol | Meaning | Unit |
|---|---|---|
| PS | Producer surplus | $ (currency) |
| Q | Quantity supplied at market price | units |
| P_market | Actual market price | $ |
| P_min | Minimum acceptable price (supply intercept) | $ |
Example 1
Market price = $40. Supply curve: P_min = $10 at Q = 0, Q = 150 at P = $40.
PS = ½ × 150 × (40 − 10) = ½ × 150 × 30
PS = $2,250 (total producer surplus in this market)
Example 2
A $10 per unit subsidy raises effective price to $50, increasing Q to 200. New PS?
PS = ½ × 200 × (50 − 10) = ½ × 200 × 40
PS = $4,000 (producers gain $1,750 from the subsidy)
When to Use It
- Analyzing market intervention effects (subsidies, price floors)
- Trade policy evaluation (tariffs and their welfare effects)
- Calculating deadweight loss from monopoly or taxation
- Introductory and intermediate microeconomics courses