How to Calculate Marginal Revenue: Formula and Worked Example
Marginal revenue is the extra money from selling one more unit. Here is the formula, a worked example, and the MR = MC rule that tells you when one more sale is worth making.
Marginal revenue is the extra money you earn from selling one more unit. To find it, divide the change in total revenue by the change in quantity:
MR = ΔTR ÷ ΔQ. It usually comes in below your selling price, and it shrinks as you sell more.
Once you can measure marginal revenue, you can price more deliberately, spot the moment effort stops paying off, and decide when to scale or stop. No economics background needed. This guide walks through what it means, the formula, a full worked example, and how to weigh it against cost.
What marginal revenue measures
Marginal revenue (MR) is the change in total revenue when you sell one more unit. Total revenue is everything you have taken in so far, and quantity is how many units you have sold. Marginal revenue ignores both totals and looks only at the gap between one quantity and the next.
Picture tutoring. You take one student, then a second. Your income rises, and the size of that rise, not your total income, is the marginal revenue of the second session.
A common myth says marginal revenue equals price. It usually does not. The moment you offer a bulk discount or shade your price to win the next sale, the revenue that sale adds lands below the sticker price.
How to calculate marginal revenue
Marginal revenue is the change in total revenue divided by the change in quantity.
Find the differences first, then divide. Dividing one total by another gives you average revenue, a different number that hides the trend you care about. So subtract the two revenue figures, subtract the two quantities, and divide one by the other.
Marginal revenue across a sales schedule
Marginal revenue is easiest to read across a full schedule. Say you sell custom journals, and each extra journal adds a little less revenue than the one before, because you lean on small discounts to keep units moving.
Work down the schedule one step at a time, subtracting each revenue figure from the next.
The marginal revenue falls with every extra unit. That decline is normal. It usually points to discounts, bulk pricing, or softening demand, and it is the early signal that selling more is getting less rewarding.
Marginal revenue vs marginal cost
This is where marginal revenue earns its keep. On its own it tells you what the next sale adds. Paired with marginal cost, what the next unit costs to make, it tells you whether that sale is worth making. For the other half of the picture, see how to calculate marginal cost.
The rule is short: keep producing while the next unit earns more than it costs, and stop once they meet.
MR > MC → keep going, each unit adds profit MR = MC → the sweet spot, stop here MR < MC → stop, each unit now loses money
Picture printing flyers. The first batch is cheap and sells well. Print enough extra batches and you reach one that costs more than it brings back.
Marginal revenue is not profit. Profit only appears once you subtract cost, so profit equals marginal revenue minus marginal cost. Rising total revenue can still hide shrinking, or even negative, profit on your most recent sales.
When one more sale is worth it
Marginal revenue turns a vague instinct, is one more worth it?, into a number you can check. Measure what the next unit adds, compare it against what that unit costs, and let the gap guide the call. You do not need an economics degree to make that comparison. You need the two numbers and the rule above.
Common questions
Ask how much extra money one more sale brought in. In symbols, that is the change in total revenue divided by the change in quantity: MR = ΔTR ÷ ΔQ.
Total revenue is every dollar you have earned. Marginal revenue is only the dollars added by the most recent unit. Total revenue is the paycheck. Marginal revenue is what one extra hour of overtime adds to it.
For a profitable sale, yes. When marginal revenue sits above marginal cost, each unit adds profit. Once it drops below, the unit costs more to make than it earns.
No. Anyone weighing whether one more of something is worth it, an extra client, an extra shift, an extra batch, is using marginal-revenue thinking, whether or not they attach a number to it.
