How to Calculate Payment Processing Fees

When you accept a card payment, the processor doesn't just hand you the full amount. There's a fee — usually a percentage of the transaction plus a small fixed charge — deducted before the money hits your account.

The basic formula

Most processors use the same structure:

Fee = (amount × percentage) + fixed fee

For example, if your processor charges 2.9% + $0.30 and you sell something for $100:

• Percentage fee: $100 × 2.9% = $2.90
• Fixed fee: $0.30
• Total fee: $3.20
• You receive: $96.80

The effective rate — what you actually pay as a percentage — is 3.20% in this case. That's higher than the advertised 2.9% because the fixed fee bites harder on small transactions.

Why the fixed fee matters more on small amounts

On a $10 transaction with the same 2.9% + $0.30 rate:

• Fee: $0.29 + $0.30 = $0.59
• Effective rate: 5.9%

That's double the advertised rate. This is why micro-merchants and low-ticket sellers often feel like fees are higher than promised — the fixed component inflates the effective percentage on small amounts.

Try it yourself

Use our Stripe fee calculator or PayPal fee calculator to see exactly what you'd keep on any transaction amount. The calculator shows your net payout instantly — no math required.

Other costs to watch for

The percentage + fixed fee is just the base. Depending on your processor and transaction type, you may also pay:

• Currency conversion fees — if you sell internationally and the buyer pays in a different currency. See our Wise fee calculator for an example of how transfer fees work across currencies.
• Chargeback fees — typically $15–$25 per dispute, regardless of outcome.
• Monthly or PCI compliance fees — some processors charge a flat monthly fee on top of per-transaction costs.
• Instant payout fees — getting your money same-day instead of the standard 1–2 day window often costs an extra 0.5%–1.75%.

Compare processors before you commit

Not all processors charge the same rate. Our payment fees calculator hub lets you compare Stripe, PayPal, Square, Venmo Business, Cash App Pay, and more — side by side, for your specific country.