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Card fee break-even calculator
Find out how much a card payment really costs you on each sale, as a share of your margin, and the smallest sale where the fee stays within a limit you set.
What this tells you
Card fees are usually quoted as a percentage of the sale, but what matters to a small business is how much of the profit on that sale they take. A 1.75% fee on a £3 item with a 65% margin is about 5p, or roughly 2.7% of the margin. Add a 10p fixed fee per transaction and the same sale now loses about 15p, over 7% of the margin.
That's why low-value, high-volume businesses (coffee shops, bakeries, market stalls, vending) should pay close attention to fixed per-transaction fees, while businesses with larger sales can mostly ignore them. If your results show fees taking a big bite out of small sales, compare providers with no fixed fee using the card machine fees calculator.
Card fees are only one running cost that eats into margin. For cafés, bakeries and other shops with fridges, ovens or long opening hours, energy is often a bigger monthly bill, and there's no price cap on business energy. Our sister site explains how contracts, renewal windows and deemed rates work in its business energy comparison guide.
The formula
Fee per sale = price × percentage fee + fixed fee. Margin per sale = price × margin %. The fee stays below your limit when price × percentage + fixed fee < limit × price × margin, so the smallest qualifying price is fixed fee ÷ (limit × margin − percentage). If the percentage fee alone is already above your limit, no price will work and you need a cheaper rate instead.
Worked example
| Sale | Fee (1.75% + 10p) | Margin at 65% | Fee as share of margin |
|---|---|---|---|
| £2.00 | £0.135 | £1.30 | 10.4% |
| £5.00 | £0.1875 | £3.25 | 5.8% |
| £20.00 | £0.45 | £13.00 | 3.5% |
With a 5% limit, the smallest sale that qualifies is 10p ÷ (5% × 65% − 1.75%) = £6.67. Below that, the 10p fixed fee pushes the cost over the limit. Rates here are illustrative.
Frequently asked questions
What margin should I enter?
Why is there a minimum sale price?
Can I set a minimum card spend?
Where do I find my fee rates?
Last reviewed 14 October 2026 by Oliver Burton. Editorial policy.