Payment Processing Fees: Percentage + Fixed Fee
Understand percentage-plus-fixed transaction fees, effective fee rates, and how to work backwards from a target payout.
A common payment-processing price has two pieces: a percentage of the transaction and a fixed amount. That structure is easy to calculate once, but it can be misleading when comparing small and large transactions or when you need to receive an exact amount after fees.
The standard calculation
For a $100 charge at 2.9% + $0.30:
$100 × 0.029 = $2.90
$2.90 + $0.30 = $3.20 total fee
The estimated net amount is $96.80.
Why the effective rate changes
On a $10 transaction, a $0.30 fixed fee is already 3% before the percentage component is applied. On a $1,000 transaction it is only 0.03%. This is why microtransactions can have a much higher effective fee rate.
Calculate the amount required for a target payout
If you want to receive $100 after a 2.9% + $0.30 fee, the correct formula is:
charge = (target + fixed fee) ÷ (1 − rate)
(100 + 0.30) ÷ 0.971 ≈ 103.30
Simply adding 2.9% + $0.30 to $100 is slightly too low because the percentage applies to the higher amount you charge.
Other fees to look for
- Cross-border or international card fees
- Currency conversion
- Chargeback or dispute fees
- Instant payout charges
- Monthly platform or gateway fees
- Marketplace commissions
- Taxes applied to processing fees
Compare providers using your own transaction mix
A lower percentage is not automatically cheaper if the fixed fee is higher, and a subscription plan is not automatically better if your volume is low. Run several realistic transaction sizes instead of comparing one headline rate.
Passing fees to customers
Surcharging rules can depend on local law, card-network rules, contract terms, and payment method. Use this calculator for arithmetic, not as legal advice about whether a fee may be passed on.