Flat-Rate vs. Interchange-Plus Calculator
Estimate and compare the monthly cost of a flat-rate processing plan and an interchange-plus plan at your sales volume. Results are estimates only — actual costs vary by card type, transaction method, industry, chargebacks, and other factors.
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Shared Inputs
Enter your monthly totals from your processing statement or quote.
Total card sales processed per month
Total card transactions per month
Flat-Rate Plan
Enter the rates from your flat-rate processor quote or agreement.
e.g. enter "2.6" for 2.6%
e.g. enter "0.10" for $0.10
Gateway, PCI, statement fees, etc.
Interchange-Plus Plan
Enter the figures from your interchange-plus quote. The processor markup is not the complete rate — interchange and assessment costs are added on top.
Blended interchange + network fees, e.g. "1.80"
The "+ 0.25%" part of interchange + 0.25% + $0.10
The "+ $0.10" part of interchange + 0.25% + $0.10
Gateway, PCI, statement fees, etc.
Fill in the inputs and click Calculate & Compare to see results.
Understanding the Two Pricing Models
How flat-rate pricing works
Flat-rate processors charge a single blended percentage — and usually a small per-transaction fee — on every card sale, regardless of the card type or how the transaction is processed. The processor absorbs the variation in underlying interchange costs and builds a margin into the single published rate. Examples of flat-rate providers include some of the most widely advertised services in the market.
The appeal is simplicity: one rate on your statement, easy to forecast, no surprises from premium card types. The tradeoff is that businesses processing a high share of low-cost debit transactions may overpay, because they effectively subsidize merchants who accept a larger share of high-interchange rewards cards.
How interchange-plus pricing works
Interchange-plus (also called cost-plus) pricing passes through the actual interchange rate set by the card networks for each individual transaction, then adds a fixed processor markup on top. The markup is stated as a percentage and a per-transaction fee — for example, interchange + 0.30% + $0.10. The interchange rate itself is set by Visa, Mastercard, Discover, and American Express, and varies by card type, industry code, and how the card is presented.
The processor markup portion is what you negotiate with the processor. The interchange and assessment costs are pass-through costs that no processor controls. This separation is why an interchange-plus processor markup is not the complete processing rate — the total effective rate will always be higher than the quoted markup alone.
Why the cheaper option depends on your business
There is no universally correct answer. Key variables include:
- Card mix — if most of your customers pay with basic debit cards, actual interchange may be lower than the flat rate; if most pay with premium rewards cards, the opposite may be true.
- Transaction size — per-transaction fees matter more for small-ticket businesses with many low-value transactions.
- Monthly volume — interchange-plus markup rates are sometimes negotiable at higher volumes, affecting the comparison.
- Monthly fixed fees — some plans include gateway, PCI, or statement fees that affect the total cost regardless of volume.
- Predictability preference — flat-rate billing is consistent month to month; interchange-plus costs shift with your card mix.
See the full guide: Flat-Rate vs. Interchange-Plus vs. Tiered Pricing Explained.
How to locate the required figures in a processing quote
For a flat-rate quote: the percentage and per-transaction fee are usually prominently displayed in the pricing schedule or proposal summary. Monthly fixed fees such as a gateway fee, PCI compliance fee, or statement fee are typically listed as line items separately.
For an interchange-plus quote: look for language such as interchange + [X]% + $[Y] per transaction. The interchange-and-assessment figure used in this calculator is an estimate you supply — check your current statement for your actual blended interchange rate, or use a typical blended estimate for your card mix (often in the range of 1.5%–2.0% for a retail mix, though it varies significantly). Monthly fixed fees are listed separately on the quote.
For guidance on reading the figures on your statement, see How to Read a Merchant Processing Statement.
Limitations of the estimate
This calculator produces estimates based on the inputs you provide. Actual costs can differ for several reasons:
- Interchange rates are set by card networks and vary by card type, merchant category code, transaction entry method (card-present vs. card-not-present), and other factors. The blended average you enter may not match your actual card mix.
- Assessment fees (charged by networks on top of interchange) vary and change periodically.
- Chargebacks, retrieval requests, and dispute fees are not included in this model.
- Some plans include tiered pricing on specific card types or transaction categories not captured by a single percentage.
- Contract terms, early-termination fees, and equipment costs are not reflected in monthly cost estimates.
- Monthly volume and transaction count naturally fluctuate, so any single-month calculation is illustrative only.
For a full checklist when comparing quotes, see How to Compare Merchant Processing Quotes.
Frequently Asked Questions
Related Resources
Educational Disclaimer
This calculator is provided for educational and illustrative purposes only. Results are estimates based on the inputs you enter and simplified formulas. Actual processing costs depend on your specific card mix, processor agreement, card network rules, and other factors not captured here. Merchant Fee Analyzer does not recommend any specific processor, guarantee any savings, or provide professional financial or legal advice. Always review your actual agreement and consult a qualified advisor before making business decisions.