Marginal Revenue Calculator

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Walk-through

How to Use This Calculator

3 steps

1

Enter the change in revenue

Enter how much your total revenue changed (ΔR) after selling more or fewer units. This can be negative — for example, if a price cut caused revenue to fall even though you sold more units.

2

Enter the change in quantity

Enter how many additional units you sold (ΔQ). The calculator divides the change in revenue by this number to get marginal revenue per unit. It updates instantly as you type.

3

Compare against marginal cost

Switch to the vs Marginal Cost tab and enter what it costs to produce one more unit. When marginal revenue equals marginal cost (MR = MC), you're at the profit-maximizing output level — producing more or less would reduce profit.

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Reference

Formula & Methodology

2 formulas

Marginal revenue

MR = ΔR / ΔQ

Marginal revenue (MR) is the change in total revenue (ΔR) divided by the change in quantity sold (ΔQ). It measures how much extra revenue one additional unit sold brings in — not the average price or total revenue. ΔQ must not be zero, since a zero change in quantity has no defined marginal revenue.

Profit-maximizing output

MR = MC

A business maximizes profit at the output level where marginal revenue equals marginal cost (MC), the cost of producing one more unit. If MR is above MC, producing more adds profit. If MR is below MC, the last unit cost more to make than it earned, so cutting output adds profit.

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Glossary

Key Terms Explained

6 terms

Marginal revenue (MR) The additional revenue earned from selling one more unit of a good or service, calculated as the change in total revenue divided by the change in quantity sold.

Change in revenue (ΔR) The difference in total revenue between two output levels — the revenue at the new quantity minus the revenue at the original quantity. Can be positive or negative.

Change in quantity (ΔQ) The difference in units sold between two output levels. Must be non-zero for marginal revenue to be defined.

Profit maximization The output level at which a business earns the highest possible profit, found where marginal revenue equals marginal cost (MR = MC).

Marginal cost (MC) The additional cost of producing and selling one more unit of a good or service. Comparing MC to MR shows whether expanding output is profitable.

Demand curve The relationship between the price of a good and the quantity buyers are willing to purchase at that price. A downward-sloping demand curve is why marginal revenue for most sellers declines as sales volume rises.

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Scenarios

Real-World Examples

3 worked examples

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SaaS upsell

Revenue rises with volume

Change in revenue (ΔR) $500 Change in quantity (ΔQ) 10 units

MR = $500 / 10 = $50 per unit. Each additional subscription sold adds $50 in revenue. Compare this to what it costs to serve one more customer to see if pushing for more sign-ups is worth it.

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Profit-maximizing manufacturer

MR equals MC

Change in revenue (ΔR) $500 Change in quantity (ΔQ) 10 units Marginal cost $50

MR = $50 per unit, exactly matching the $50 marginal cost. This output level is the profit-maximizing point — producing one more or one fewer unit would reduce total profit.

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Retailer running a markdown

Declining (negative) marginal revenue

Change in revenue (ΔR) -$300 Change in quantity (ΔQ) 25 units

MR = -$300 / 25 = -$12 per unit. Selling 25 more units through a price cut actually reduced total revenue — the lower price applied to every unit sold, not just the extra ones. This is a sign the price cut went too far past the revenue-maximizing point.

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Deep Dive

Understanding the Marginal Revenue Calculator

3 chapters · 3 min read

Marginal revenue tells you what one more sale is actually worth — not your average price, not your total revenue, but the extra dollars a single additional unit brings in. It's the key number behind pricing, production, and output decisions for any business.

How the Marginal Revenue Calculator works

The calculator divides the change in total revenue (ΔR) by the change in quantity sold (ΔQ): MR = ΔR / ΔQ. Both values come from comparing two output levels — before and after a change in sales volume. If revenue rose by $500 when you sold 10 more units, marginal revenue is $50 per unit.

Marginal revenue can be negative. That happens when the price cut needed to sell more units reduces revenue on every unit sold — including the ones you were already selling at the old price — by more than the extra units add.

Inputs and what they mean

Change in total revenue (ΔR) is the dollar difference in revenue between two output levels; it can be positive or negative. Change in quantity sold (ΔQ) is the difference in units between those two levels, and must not be zero — a change of 0 units has no defined marginal revenue. Marginal cost (optional, on the vs Marginal Cost tab) is what it costs to produce one more unit; comparing it to marginal revenue tells you whether expanding output adds profit.

Limits and edge cases

Marginal revenue assumes the revenue change you enter reflects only the quantity change — not a separate factor like a seasonal spike or a one-time promotion unrelated to volume. For a perfectly competitive firm, marginal revenue equals price and stays constant; for most real-world sellers (who must lower price to sell more), marginal revenue declines as volume rises and eventually turns negative. This calculator reports MR for the specific ΔR/ΔQ you enter — it does not model an entire demand curve. For production decisions, always pair marginal revenue with marginal cost rather than acting on MR alone.

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Questions

Frequently Asked Questions

6 questions

What is the formula for marginal revenue?+

Marginal revenue equals the change in total revenue divided by the change in quantity sold: MR = ΔR / ΔQ. It measures the extra revenue earned from one additional unit sold.

How do I find the profit-maximizing output level?+

Profit is maximized where marginal revenue equals marginal cost (MR = MC). If MR is above MC, producing more adds profit; if MR is below MC, the last unit cost more than it earned, so cutting output adds profit.

Does marginal revenue always decline as you sell more?+

Usually, yes, for most real-world sellers. Because reaching additional buyers typically requires a lower price, and that lower price applies to every unit sold, marginal revenue tends to fall — and can even turn negative — as sales volume increases. A firm in a perfectly competitive market is an exception: it can sell any quantity at the market price, so its marginal revenue stays constant and equals price.

How is marginal revenue different from price?+

For a price-taking firm in a competitive market, marginal revenue equals price, since selling one more unit doesn't require lowering the price on units already sold. For a firm with pricing power (such as a monopolist), marginal revenue is below price, because increasing sales volume requires cutting the price on all units sold, not just the additional one.

What units does marginal revenue use?+

Marginal revenue is expressed in dollars per unit ($/unit) — the additional revenue earned per additional unit sold. The change in revenue you enter should be in dollars and the change in quantity in whole units.

What does it mean if marginal revenue is below marginal cost?+

It means the last unit produced cost more to make than it earned in revenue. Cutting output at that point increases total profit, since each of those unprofitable units is dragging total profit down.

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