A credit card processing fee calculator applies the rate in your processor agreement to a transaction amount. The common flat-rate formula is transaction amount multiplied by the percentage rate, plus the fixed per-transaction charge. On a $100 transaction at 2.9% plus $0.30, the percentage portion is $2.90, the fixed portion is $0.30, the total processing fee is $3.20, and the estimated net payout is $96.80.
There is no universal credit card processing rate. Pricing can change with the processor, country, sales channel, card origin, entry method, merchant category, plan, volume, currency conversion, and negotiated agreement. Stripe's official U.S. pricing page lists 2.9% plus $0.30 for a successful domestic online card transaction, while Square's U.S. pricing page lists 2.6% plus $0.15 for many in-person payments. These are product-specific examples, not market-wide defaults. The calculator keeps every rate editable and was reviewed August 22, 2026.
What is the credit card processing fee formula?
For a flat percentage plus fixed charge, use: processing fee = transaction amount × percentage rate + fixed fee. Convert the percentage to decimal form before multiplying. A 2.9% rate becomes 0.029. Card processors usually round a charged fee to currency precision, so the calculator rounds the combined transaction fee to cents.
The payout formula is transaction amount minus processing fee and any other deducted charges. Keep payout separate from profit. Payout is what remains after modeled processor costs. Profit also subtracts inventory, payroll, shipping, software, taxes, refunds, and other business expenses. This tool estimates processing cost and payout, not full business profit.
- Percentage portion = amount × rate
- Transaction processing fee = percentage portion + fixed charge
- Total modeled fees = transaction processing fee + allocated recurring costs + verified extras
- Net payout = transaction amount - total modeled fees
- Effective rate = total modeled fees ÷ transaction amount × 100
Why is the effective processing rate higher on small sales?
A fixed charge represents a larger share of a small ticket. At 2.9% plus $0.30, a $10 payment costs $0.59, an effective rate of 5.9%. A $100 payment costs $3.20, an effective rate of 3.2%. A $1,000 payment costs $29.30, an effective rate of 2.93%. The percentage stays constant, but the fixed $0.30 is spread across more revenue as the ticket grows.
That difference matters for low-priced products, tips, donations, and micropayments. Compare providers with your actual ticket distribution rather than one average order. Also test refunds and disputes separately using official terms because their treatment is not represented by the basic percentage-plus-fixed formula.
Which costs belong in a processing-fee comparison?
Start with the percentage and fixed charge for the exact payment channel. Then identify recurring gateway, statement, platform, device, or software costs. To create a blended per-transaction estimate, divide a monthly cost by the expected number of monthly card transactions and enter that allocation. For example, a $20 monthly cost spread across 200 transactions adds $0.10 per transaction.
Add conditional charges only when the transaction qualifies. Stripe publicly lists additions for manually entered cards, international cards, and currency conversion on its U.S. pricing page. Other providers distinguish card-present, online, keyed, invoice, wallet, or virtual-terminal payments. Do not add every possible surcharge to every transaction. Use the current official pricing page and your account agreement to determine which charge applies.
How do flat-rate and interchange-plus pricing differ?
Flat-rate pricing presents a defined percentage and fixed amount for a payment type. It is straightforward to model, although separate additions can still apply. Interchange-plus pricing generally separates underlying network or card costs from a processor markup. The final expense can vary by card and transaction characteristics, so a single public percentage may not describe every payment.
For interchange-plus statements, calculate the observed effective rate from the statement total: total processing costs divided by processed card volume. Then compare that result over several representative months. Do not label a historical effective rate as a guaranteed future rate. Card mix, refunds, disputes, and volume can change it.
How do you compare two processor quotes fairly?
Use the same transaction amounts, channel, country, card mix, monthly volume, hardware assumptions, and contract period. Run at least a small, typical, and large ticket. Then include recurring charges and only the conditional fees likely to occur. A quote with a lower percentage can cost more on small orders if its fixed charge is higher, while a monthly fee can be efficient at high volume but expensive at low volume.
Example: provider A charges 2.9% plus $0.30 and provider B charges 2.6% plus $0.15. On a $25 sale, the modeled fees are $1.03 and $0.80. On a $250 sale, they are $7.55 and $6.65. Those examples compare only disclosed transaction pricing. They do not establish the total price of a provider without checking subscriptions, equipment, contract, chargeback, refund, cross-border, and account-specific terms.
What should you verify before relying on the result?
Verify the processor, product, payment channel, merchant country, card country, currency, entry method, subscription tier, and any negotiated rate. Check whether the percentage applies to the full customer payment and whether tax, tips, shipping, or other amounts enter that total. Confirm how fees are rounded and whether the fixed charge applies to zero-dollar authorizations, partial captures, refunds, or multiple captures.
Save the official pricing URL and review date with your calculation. Public pricing may not match a custom agreement, legacy plan, partner platform, or account notice. If the processor dashboard or signed agreement shows different terms, use those terms. Recheck after a pricing update and reconcile estimates against an actual statement before making a material business decision.
Sources
- Stripe: official U.S. payments pricing ↗
- Square: official U.S. processing pricing ↗
- PayPal: official U.S. merchant fees ↗
Frequently asked questions
How much is a 2.9% plus $0.30 fee on $100?
The percentage portion is $2.90 and the fixed charge is $0.30, so the modeled fee is $3.20 and payout is $96.80 before any other costs.
What is an effective processing rate?
It is total modeled processing costs divided by the transaction amount or processed volume. It captures fixed and allocated costs that a headline percentage alone misses.
Are all credit card processing fees the same?
No. Rates and fee structures vary by provider, country, channel, card, entry method, plan, volume, currency, and merchant agreement.
Should monthly fees be included?
Include them when comparing total cost. Allocate a monthly fee across expected transactions or volume, and label the allocation as an assumption.
Does net payout equal profit?
No. Net payout subtracts modeled processing charges from the payment. Profit also subtracts the product and operating costs of earning that payment.