Cost Price Calculator
Find the cost price from the selling price and a profit %, loss % or margin, with the profit or loss amount and both percentages.
Cost price is what an item cost to buy or make. When you know the selling price and the profit or loss percentage, you can work backwards to the cost — useful for checking a supplier's claims, pricing resale stock and solving school profit-and-loss problems. Profit and loss percentages here are measured on cost, the standard convention, with an extra option for margin, which is measured on the selling price.
How to use this tool
- Enter the selling price.
- Choose whether you know the profit %, the loss % or the margin %.
- Enter the percentage.
- Read the cost price, the profit or loss amount and both percentages.
Formula
Cost price = Selling price × 100 ÷ (100 + Profit %)
Cost price = Selling price × 100 ÷ (100 − Loss %)
Cost price = Selling price × (1 − Margin ÷ 100)
Profit % and loss % are fractions of the cost price, so the selling price is divided rather than reduced by the percentage. A margin is a fraction of the selling price, which is why that case is a simple subtraction. A 100% margin means zero cost; profit as a percentage of zero cost is undefined and is shown as a dash.
Example
An item sells for $540 at a 20% profit. Cost price = 540 × 100 ÷ 120 = $450, so the profit is $90 — 20% of the cost but only 16.67% of the selling price. If a $90 item was sold at a 10% loss, its cost price was 90 × 100 ÷ 90 = $100.
Frequently asked questions
Why not just take 20% off the selling price?
Because the 20% profit was calculated on the cost, not on the selling price. Taking 20% off $540 gives $432, but a 20% profit on $432 would make the price $518.40, not $540.
Is profit percentage calculated on cost or selling price?
By convention, profit and loss percentages are on cost. Margin is the same profit measured on the selling price, so always check which one a figure means.
What goes into cost price in a business?
The purchase or production cost plus costs needed to get the goods ready to sell, such as inbound freight and import duty. Selling costs like advertising are usually kept separate.
Last updated: 2026-10-30