Ecommerce unit economics calculator

Use one reporting window and a consistent measurement scope. Replace the example inputs with your own figures. The result updates locally as you type. Copy the result to your planning notes, or copy a link containing only the numeric inputs. Reset restores the illustrative example.

• Enter average order value, cost of goods, shipping, fees and return rate.
• Read contribution margin per order.
• Read break-even ROAS and max CPA that follow from it.
• Test how a price change or discount alters them.

An £80 order with £28 product cost, £4 shipping, £3 fees and £4 returns allowance contributes £41 before advertising. The margin is 51.25%, break-even ROAS is 1.95 and maximum contribution-only CPA is £41. Fifty orders and £1,200 ads leave £850 before fixed overhead.

Contribution/order = AOV - COGS - shipping - fees - returns allowance. Margin% = contribution / AOV × 100. Break-even ROAS = AOV / contribution. Maximum CPA = contribution. Contribution after ads = orders × contribution - ad spend.

Maximum CPA here is an arithmetic ceiling, not a spending recommendation. Rent, salaries, software and a profit reserve still need funding. If variable costs consume all revenue, no positive advertising allowance remains. Repeat purchases are deliberately excluded unless you have reliable cohort evidence and a clear payback policy.

Good unit economics leave room after ads for overheads and profit. If contribution is thin, no ad tweak will fix it. Look at price, cost and shipping first.

• Pricing.
• Shipping policy.
• Return rate.
• Payment fees.
• Ignoring returns.
• Using an average that hides loss making products.
• Forgetting packaging.
• Not updating after a price change.