Start with the receipt, not the percentage
A percentage printed on a pricing page is only one part of a fee rule. Before doing arithmetic, identify the provider, payment method, account terms, transaction market and received currency. An online card payment and a manually entered card may not belong to the same tariff. A recurring service charge also has a different role from a fixed charge assessed on each receipt.
PayPal is a useful example of why the method matters. The US merchant fee page distinguishes Checkout, Send/Receive Money for Goods and Services, and invoicing transactions separately. Even within invoices, the settlement method changes the applicable published row. A seller should not copy the Checkout fixed charge into a Goods and Services estimate simply because both payments use PayPal. The invoice itself does not tell you which method settled it.
Square likewise distinguishes payment channels. The NetFee Tools preview does not currently enable a Square preset because its complete plan applicability has not been established. Entering a rate from your own agreement can make a custom illustration possible, but it does not turn that illustration into a verified provider quote.
Write down the rule before calculating
For a simple additive model, identify the percentage, fixed transaction charge and gross payment amount. State whether the percentage is applied to gross and what rounding convention will be used. If there is another percentage, do not assume it uses the same base or rounds together with the first one unless the terms support that treatment.
Under the site's supported convention, the transaction formula is:
- Percentage charge = gross × percentage ÷ 100, rounded once to cents.
- Total fee = rounded percentage charge + fixed cents.
- Net receipt = gross − total fee.
For a synthetic $100 payment at 3% plus $0.30, percentage cost is $3.00. Total cost is $3.30, leaving $96.70. These inputs are made up for teaching; they are not a universal processor rate.
Fixed charges make small payments different
In that synthetic example, the nominal percentage is 3%, but the total fee is 3.30% of gross because the $0.30 fixed charge contributes another 0.30 percentage points. Effective rate is total fee divided by gross, expressed as a percentage. It is a description of the modeled payment, not another quoted tariff.
Transaction count matters for the same reason. One hundred payments can incur one hundred fixed transaction charges. It would be misleading to apply a single fixed charge to an entire month's sales when the agreement assesses it per transaction.
Rounding is an assumption that deserves a label
NetFee Tools' published-rate options use half-up rounding on the percentage once, followed by fixed cents. Half-cent ties round upward. This is an explicit site convention, not a verified Stripe or PayPal rounding policy. A published percentage and fixed charge do not by themselves establish how a provider resolves a half-cent tie.
Custom mode also offers half-even. Selecting it changes the model; it does not verify that the provider uses it. If your statement differs by a cent, check the rounding scope, actual transaction terms and any extra charges before concluding that either figure is wrong.
Monthly estimates require more information
The general processing calculator accepts transaction count, average ticket and a recurring monthly cost. It rounds one assumed ticket, multiplies that fee by count, then adds the recurring amount once. In the synthetic example of 100 identical $100 payments at 3% plus $0.30 and $20 recurring cost, gross is $10,000, processing cost is $330, total modeled cost is $350 and net is $9,650.
The word identical is essential. A real mix of tickets can produce different rounding even when its average and total gross agree with those assumptions. Use actual transaction-level fees for reconciliation; use the average-ticket result for planning under disclosed assumptions.
Choose the next calculation
Use the Stripe page only for its supported domestic online card scope, or custom terms. Use the PayPal page to select the specific receipt or invoice method. Use Square custom mode with your applicable plan and channel. Use the general processing page for synthetic or agreement-based transaction and monthly estimates.
A fee estimate does not include every refund, dispute, tax, exchange, payout, hardware or subscription adjustment. It also does not establish provider acceptance limits or permission to surcharge a customer. Keep those questions separate from the arithmetic.
Choose a calculator for your payment
Official sources and calculation assumptions
- Stripe official pricing — Standard domestic card components and exclusions.
- PayPal US merchant fees — payment methods, domestic conditions and invoice fees.
- Square official fee calculator — payment channels; no Square preset is enabled here.
Published pricing does not establish provider rounding behavior. These examples use the stated site convention and do not guarantee actual statement charges. NetFee Tools is an independently operated personal project, not officially affiliated with these providers.
Read the calculation methodology and source-review policy · Contact and corrections status