How to Calculate Producer Surplus
Producer surplus is the area above the supply curve and below the price, for a straight-line supply curve, ½ × quantity × (price − minimum acceptable price).
The Producer Surplus formula
Calculator
Enter the market price, the supply intercept and the quantity to get the producer surplus triangle.
The price sellers receive.
The lowest price at which any seller would supply, where supply meets the price axis.
Units traded at that price.
Sellers collect $90 above what they would have accepted, the triangle above supply and below the $8 price.
- Height (price − supply intercept)
- $6
- Average surplus per unit
- $3
The vertical side of the triangle: how far the market price sits above the lowest price any seller would accept.
Half the height: the surplus spread evenly across every unit sold.
How to calculate Producer Surplus, step by step
- 1Find the market price and quantity. The equilibrium price and quantity sold (or the given price).
- 2Find the supply curve's price intercept. The lowest price at which any seller would supply, where supply meets the price axis.
- 3Compute the triangle. Height = price − supply intercept; base = quantity. Producer surplus = ½ × base × height.
Worked example: Producer Surplus
If supply meets the price axis at $2, the market price is $8, and quantity is 30, producer surplus = ½ × 30 × (8 − 2) = ½ × 30 × 6 = $90.
When the sellers come as a list, not a curve
Plenty of questions give a table of what each seller would accept rather than a supply equation. The triangle formula does not apply, because there is no curve to take the area under. Add the sellers up one at a time instead.
Suppose five sellers each have one unit to sell and would accept $2, $4, $6, $8 and $10, and the price is $7. The two whose costs sit above $7 do not sell, since producing something that costs more than the price loses money. The three who do sell keep (7 − 2) + (7 − 4) + (7 − 6) = $9 between them.
That is the mirror image of consumer surplus. Every seller who trades keeps the gap between the price and the lowest price they would have accepted, and the triangle is only what that sum looks like once there are enough sellers for the steps to smooth into a line.
Producer surplus is not profit
This is the distinction examiners test most often on this page. Producer surplus is revenue minus VARIABLE cost. Profit is revenue minus TOTAL cost. The gap between them is fixed cost.
So the worked example above gives a producer surplus of $90. If the firm also pays $60 in rent that it owes whether it produces or not, profit is 90 − 60 = $30. Producer surplus stayed at $90 the whole time, because rent is not part of it.
The consequence matters for short-run shutdown questions. A firm with positive producer surplus but negative profit is losing money and should still keep producing in the short run, because the surplus is covering part of a fixed cost it cannot escape. Shutting down would leave it paying the whole rent and earning nothing toward it.
What moves it, and in which direction
A higher price raises producer surplus twice over: existing units earn more per unit, and units that were not worth producing before become worth producing. That is why the region grows into a taller and wider triangle rather than just a taller one.
A rightward shift in supply looks ambiguous and is not. Each unit costs less to make, which pushes surplus up, but the price falls too, which looks like it should push surplus down. Write the triangle out and the ambiguity disappears: with supply P = c + dQ, producer surplus is ½ × Q × (P − c), and P − c is just dQ, so the whole thing collapses to ½ × d × Q². It depends on quantity alone. A rightward shift always raises quantity, so as long as the curve shifts without changing its steepness, producer surplus always rises. The falling price never wins, however steep demand is.
A binding price floor is the genuinely ambiguous case. It raises the price on the units that still sell but cuts how many sell, the region becomes a trapezoid rather than a triangle, and which effect dominates depends on the numbers. Compute both areas rather than reasoning from the direction.
Producer Surplus questions
What is the difference between producer surplus and profit?
Producer surplus is price minus the seller's marginal cost on each unit, ignoring fixed costs; profit subtracts total cost. In the short run they differ by fixed costs.
What increases producer surplus?
A higher market price or a rightward demand shift raises producer surplus; a price ceiling below equilibrium or a tax on sellers shrinks it.
How do you get total surplus?
Total surplus = consumer surplus + producer surplus, the whole triangle between demand and supply up to the equilibrium quantity. It is maximized at competitive equilibrium.
Get AP Econ exam tips in your inbox
Occasional emails with study tips, new interactive graphs, and exam-season reminders. Free, no spam.
No spam. Unsubscribe anytime. Read our privacy policy.
Keep track of what you have studied
A free EconLearn account adds progress tracking, your quiz history, and achievements. Studying here is free either way, and there is nothing to pay for as a student.
Create a free accountAlready have one? Sign in
Last updated