Producer Surplus vs Total Surplus
Producer Surplus and Total Surplus are two Supply & Demand concepts in AP Economics that students often mix up. Producer surplus is the difference between the minimum price a producer is willing to accept and the actual price they receive. Total surplus is the sum of consumer surplus and producer surplus. Here is how they compare side by side.
It measures the net benefit producers receive from selling a good or service. On a supply curve, it is the area above the supply curve and below the price received, up to the quantity sold.
It represents the total net benefit to society from the production and consumption of a good or service. At the equilibrium price and quantity, total surplus is maximized.
Producer Surplus vs Total Surplus: Why a Bigger Slice Can Mean a Smaller Pie
| Producer Surplus | Total Surplus | |
|---|---|---|
| Whose gain it counts | Sellers only | Buyers and sellers together, adjusted for government revenue or cost |
| Area on the diagram | Between the price received and the supply curve | Between the demand curve and the supply curve, out to the quantity traded |
| How it is built | Price received minus the lowest acceptable price, added up over every unit sold | Producer surplus plus consumer surplus, minus any subsidy the taxpayer funds |
| Effect of a binding price floor | Can rise or fall, since each sale pays more but fewer sales happen | Always falls, because mutually beneficial trades are blocked |
| Effect of a per unit subsidy to sellers | Rises | Falls once the taxpayer cost is counted |
| Effect of monopoly pricing | Rises, since the firm charges above marginal cost | Falls, since output is held below the efficient quantity |
| What it says about efficiency | Nothing alone, since it can grow while the market moves away from the efficient quantity | It is the efficiency test, and it peaks at the competitive quantity |
A subsidy hands sellers more surplus than the market as a whole gains
Producer surplus is a slice; total surplus is the whole pie, net of what the public paid for it. Follow an illustrative market with demand of price equals 90 minus 2 times quantity and supply of price equals 10 plus 2 times quantity. They cross at a quantity of 20 and a price of 50, giving producer surplus of one half times 20 times 40, which is 400. Consumer surplus is also 400, so total surplus is 800. Now the government pays sellers 20 per unit. Buyers end up paying 40, sellers end up receiving 60, and 25 units trade. Producer surplus becomes one half times 25 times 50, which is 625, a gain of 225. Consumer surplus reaches 625 as well. But the subsidy costs taxpayers 20 times 25, or 500, and that money has to be subtracted. Total surplus is 625 plus 625 minus 500, which is 750, down 50 from where it started. Sellers gained 225 while the economy lost 50, because the last 5 units cost more to produce than buyers valued them at. The mechanics of that per unit calculation are set out at /calculate/per-unit-subsidy.
Producer surplus is not profit, and total surplus is not revenue
Two vocabulary slips cost marks on nearly every welfare question. The first is treating producer surplus as profit. Producer surplus is revenue minus the total variable cost of what was produced, so in the short run it exceeds economic profit by the amount of fixed cost. A firm can enjoy positive producer surplus and still be losing money, which is exactly why a firm keeps operating below break even as long as the price covers average variable cost. The second slip is treating total surplus as the size of the market. Revenue is price times quantity, an amount of money changing hands. Total surplus is the value created by that exchange, adding what buyers got over what they paid to what sellers got over what production cost them. A market can carry enormous revenue and small total surplus if the price sits far from the competitive level. When a question asks about a change in welfare, measure areas between the curves, not rectangles of spending. The area calculation itself is drilled at /calculate/producer-surplus.
Frequently asked questions
Is producer surplus the same as profit?
No, producer surplus equals revenue minus total variable cost, so it is larger than economic profit by the amount of fixed cost. In the long run, when no cost is fixed, the two measures converge, but on a short run diagram they are different areas.
Does a subsidy increase producer surplus?
Yes, a per unit subsidy raises the price sellers receive and raises the number of units sold, so producer surplus increases on both counts. Total surplus still falls, because the extra units cost more to produce than buyers value them at and taxpayers fund the difference.
How do you find producer surplus on a supply and demand graph?
It is the area above the supply curve and below the price line, measured out to the quantity traded. With a straight line supply curve and no policy in place that area is a triangle equal to one half times the quantity traded times the gap between the price and the vertical intercept of supply.
Live Supply and Demand graph. Drag the curves, or open the full version.
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