How to Use This Tool
Put each fee structure on a line as name, percent, fixed, monthly. Set your real average
order value, because that is what decides the answer.
The fixed fee is the variable one
A charge of "2.9% + 0.30" has two parts that behave completely differently. The percentage scales with the order; the fixed amount does not, so its weight falls as the order grows.
At a five-unit order the 0.30 alone is 6% and the total is 8.90%. At 100 the same structure is 3.20%, and at 500 it is 2.96% — finally close to the advertised figure. A business selling coffee and a business selling furniture on identical terms pay entirely different rates.
Which is why "cheapest processor" is not a question with a general answer. It depends on your average order value, and the number quoted in marketing is the limit approached from above.
Two plans cross at exactly one point
Comparing 2.9% + 0.30 against 1.9% + 0.50: the second has a better percentage and a worse fixed fee, so one is better below some order value and the other above it. Setting the two equal gives the crossover directly:
crossover = (fixed₂ − fixed₁) ÷ (percent₁ −
percent₂)
Here that is (0.50 − 0.30) ÷ 0.01 = 20.00. Below 20 the first plan wins; above it the second does. Nothing about the marketing makes that visible, and it is a single division.
Refunds usually cost twice
Many processors keep their fee when a transaction is refunded, and some charge a further fee to process the refund. So a refunded order costs you the goods, the shipping, and the processing fee on money you no longer have.
At a 4% refund rate the effect is modest. In categories where returns run at 20–30% — clothing especially — the fee on refunded orders becomes a real line item that never appears in a margin calculation done on the sale price.
Why rates are not built in
You have to type them, and that is deliberate. Processor pricing varies by:
- Country, both yours and the customer's, with cross-border surcharges that are often larger than the base rate.
- Card type — commercial and premium consumer cards cost noticeably more than standard debit.
- Whether the card is present, with in-person rates typically lower than online.
- Volume, with negotiated rates for larger merchants.
- Time — published rates change, and any table baked into a page is wrong within a year without saying so.
Take the numbers from your own statements rather than from a marketing page. A statement shows what you actually paid, including the surcharges nobody advertises.
What else to weigh
Fees are comparable and rarely the whole decision. Payout timing affects cash flow; chargeback handling and fees differ; a processor that declines legitimate transactions costs far more in lost sales than any rate difference; and integration effort is real. A plan that is 0.3% cheaper and blocks 2% of your customers is not cheaper.
