How credit card processing fees are calculated
A percentage-plus-fixed-fee plan charges a percentage of card volume, a fixed amount for every transaction, and sometimes a monthly platform or service fee. This calculator combines all three so plans can be compared at the same sales volume.
Example comparison
At 100 monthly transactions averaging $100, Plan A at 2.9% + $0.30 costs $320. Plan B at 2.6% + $0.10 plus $29 monthly costs $299, saving $21 per month.
Same volume, many small transactions
At 1,000 transactions averaging $10, both plans process $10,000. Plan A costs $590, while Plan B costs $389. The lower fixed fee makes Plan B cheaper by $201 per month.
Same volume, fewer large transactions
At 20 transactions averaging $500, Plan A costs $296 and Plan B costs $291. With fewer fixed charges, Plan B's advantage falls to $5 per month.
Why average transaction size matters
A lower percentage rate matters more for large tickets. A lower fixed fee matters more when you process many small transactions. Monthly fees can be worthwhile only after enough volume offsets them.
What is an effective processing rate?
The effective rate divides all estimated processing costs—including fixed and monthly fees—by total card volume. It makes differently structured quotes easier to compare.
How much is a 2.9% + $0.30 processing fee?
On a $100 card payment, 2.9% is $2.90 and the fixed fee is $0.30, for a total of $3.20. On a $10 payment, the fee is $0.59, so the effective rate is much higher at 5.9%.
When is a monthly processing fee worthwhile?
A monthly fee is worthwhile only when savings from lower transaction rates exceed the recurring charge. Compare the plans using your real transaction count and average ticket instead of sales volume alone.
What costs should be added to a processor quote?
Include every recurring or transaction-based cost you expect: statement or platform fees, PCI fees, chargebacks, gateway charges, international surcharges, hardware, minimums, and any tiered or interchange markup. This calculator directly models only the percentage, fixed, and monthly components.
Assumptions and limitations
- The sample rates are editable examples, not claims about a specific processor.
- Interchange-plus, tiered pricing, minimum fees, caps, chargebacks, hardware, PCI fees, international surcharges, and taxes on fees require separate adjustments.
- Use the exact quote or statement rates you received and verify contract terms before switching processors.
Last reviewed: September 12, 2026 · See an issue? Request a correction.