Unit Economics Calculator
Enter the price and every cost that comes with one order. You get the contribution per order, the margin, the profit at your volume and the price that reaches your target margin.
Worked examples
A £50 product
Cost £15, packaging £1, postage £4, card fee 1.5% + 20p, no refunds
£29.05 per order, 58.1% margin
£50 - £0.95 card fees - £15 - £1 - £4 = £29.05, which is 58.1% of £50.
The same product with refunds and commission
10% commission, 10% refunded, half of refunds resold
£20.30 per order, 45.1% margin
Revenue kept is £45. Costs are £0.95 fees, £4.50 commission, £14.25 product and £5.00 packaging and postage.
Pricing for a 40% margin
The same costs, target margin 40%
£44.71
Below this price the margin falls under 40% once refunds and commission are counted.
About Unit Economics Calculator
Unit economics looks at one sale at a time. After you take off everything that grows with each order, such as the product, packaging, postage, card fees, commission and refunds, what is left is the contribution. Fixed costs like rent and software have to be covered from the contribution of all your orders, so if a single order contributes little or nothing, selling more of it will not rescue the business.
This calculator handles the parts people often miss. A refunded order loses the sale but usually keeps the card fee, and the product only comes back as stock if you can sell it again. Enter the share of orders refunded and the share of refunded goods you can resell, and the tool adjusts the revenue and the product cost for you. It then shows your contribution margin, your profit for a month after fixed costs, and works backwards to find the lowest price that reaches the margin you want.
How to use Unit Economics Calculator
- Enter the selling price without VAT, and the product cost, packaging and postage you pay for one order.
- Add the card fee percentage and per order amount, and any marketplace commission.
- Enter the share of orders that are refunded and how much of that stock you can sell again.
- Add your orders and fixed costs for a month and a target margin, then read the contribution, profit and price.
Common uses
- Testing whether a product is worth selling before you buy stock
- Comparing selling on your own site with a marketplace
- Working out how far a price can fall in a sale
- Finding the price that gives a margin you can live on
Sources
Last reviewed 18 October 2026.
Frequently asked questions
What is contribution?
It is what one sale leaves after every cost that grows with each order. It contributes towards fixed costs such as rent, software and your own pay, and after those are covered it becomes profit.
How is the margin worked out?
The contribution is divided by the revenue you keep after refunds. A 40% margin means each pound of kept revenue leaves 40p after the costs that vary with orders.
Why do refunds cost more than the sale?
Because you usually lose the card fee and the postage as well as the sale, and unless you can sell the product again you lose its cost. The resale share lets you say how much of that comes back.
Should I include VAT?
Use prices without VAT if you are VAT registered, because the VAT belongs to HMRC. If you are not registered, use the price the customer pays.
What if the price for my target margin shows Not possible?
It means the percentage costs, such as commission and card fees, plus the target take up more than the whole price, so no price can reach the target. Lower the target or the percentages.