Producer surplus is the benefit a seller receives from selling units for more than the minimum needed to supply them. In the standard short-run production model, it equals sales revenue minus total variable cost.
Profit requires another step: subtracting fixed costs as well. Positive producer surplus therefore does not establish that a business is profitable.
How is it calculated?
For a single item, a seller willing to accept $5 who receives $10 gains $5 of producer surplus. For several units, add the difference for each unit sold. The minimum acceptable amount concerns the cost or opportunity forgone by supplying that unit, not simply the price the seller hoped to obtain.
In the short-run model, variable costs change with output, while fixed costs do not change over the relevant range. The University of Victoria explains producer surplus as revenue less variable cost, with relevant explicit and implicit costs included.
Producer surplus can be positive while profit is negative
Suppose a producer sells 1,000 cans for $1.20 each. Revenue is $1,200. Assume the total variable cost of supplying them is $500. Producer surplus is $1,200 − $500 = $700.
If fixed economic costs for the period are $900, economic profit is $1,200 − $500 − $900 = negative $200. The producer has $700 of surplus but makes an economic loss of $200.
CORE Econ shows the same relationship: profit equals producer surplus minus fixed costs. Economic profit includes opportunity costs; an accounting profit figure can use a different cost basis. None of these figures alone describes the timing of cash receipts and payments.
How does it appear on a graph?
With quantity on the horizontal axis and price on the vertical axis, producer surplus is the area above the relevant supply curve and below the price sellers receive, up to the quantity sold. It is not the entire area below price, which also includes variable costs.
In a separate continuous example, let supply rise from a zero price at zero units to $12 at 12 units. At a $6 price, sellers supply 6 units. The shaded triangle has a base of 6 and a height of $6, so producer surplus is $18.
The triangle formula works for this straight supply curve. Other curves or stepped supply schedules require the corresponding areas or unit-by-unit calculations. The competitive supply interpretation also depends on the model’s assumptions.
How does it compare with consumer surplus?
Consumer surplus is a buyer’s maximum willingness to pay minus the price paid. Producer surplus uses the seller’s minimum acceptable amount. Together they measure gains from trade in a basic market model.
A higher price can change the division of gains and the quantity traded. It does not guarantee a larger producer surplus, because fewer sales and changing costs can alter the result. Pricing power, competition and buyers’ responses also matter.
The model can describe different institutions; surplus is not exclusive to a political system labelled a free market. Welfare assessments may also need to include tax receipts, effects on third parties and distribution.
Alfred Marshall’s Principles of Economics was first published in 1890.
Last checked and updated on November 10, 2026 by the MBN editorial team.