Gross and net describe different amounts
Gross is the amount of the payment before the modeled processing fee. Net is what remains after that fee. A modeled net receipt is not necessarily a bank deposit: other account adjustments or services can sit outside the transaction calculation.
Suppose a synthetic custom rule charges 3% of gross plus $0.30. A $100 payment leaves $96.70 after the modeled $3.30 fee. If you want $100 after that fee, charging $100 is not sufficient. The target net is an input to another calculation, not a label you can attach to the original gross.
The applicable method still matters. A published-rate estimate must use the correct provider scenario. NetFee Tools' Stripe scope is Standard US domestic online card receipts in USD. Its PayPal options distinguish Checkout, Goods and Services, and two specifically supported invoice methods. Square currently requires custom terms; its automatic provider presets are not enabled.
Why adding a percentage to the target is insufficient
At the synthetic rate, adding 3% and $0.30 to a $100 target gives $103.30. But the fee applies to $103.30 gross, not to the original $100 target. Under site half-up rounding, the percentage fee becomes $3.10, then the fixed charge makes $3.40. Net is $99.90, short of the target.
Ignoring rounding for a moment, the equation is net = gross × (1 − rate) − fixed. Rearranging gives gross = (net + fixed) ÷ (1 − rate), where rate is expressed as a decimal fraction. That equation explains the relationship, but it does not resolve the cent-level answer when the actual model rounds a fee.
The site's reverse calculation therefore searches gross amounts in integer cents and checks the modeled net. It returns the first amount meeting the target and verifies the preceding cent, rather than just displaying a continuous formula rounded in an unspecified way.
Check the candidate and the previous cent
For the synthetic 3% plus $0.30 half-up example, minimum gross for $100 modeled net is $103.40. The unrounded percentage is $3.102, which rounds to $3.10. Add $0.30 and the fee is $3.40, leaving $100.00. At $103.39 gross, the percentage is $3.1017 and still rounds to $3.10; net is $99.99. Those two checks establish minimum gross within that model.
A Stripe published-rate example makes the same distinction with 2.9% plus $0.30 for the supported Standard US domestic online card scenario. For Standard domestic online cards, the modeled $100 target requires $103.30 gross under the site's half-up percentage-then-fixed convention. Percentage $2.9957 rounds to $3.00; adding the published $0.30 gives $3.30 fee. At $103.29, the same rounded total fee leaves $99.99.
This comparison validates arithmetic under an explicit convention. It does not document Stripe's own cent tie-breaking or promise agreement with a statement. Level B is an estimate using confirmed published rates, not fully verified provider calculation behavior.
Decide which question you are answering
A gross-to-net calculation answers what remains from a payment under the stated fee model. A reverse calculation answers the modeled gross required for a target. Neither determines what a customer has agreed to pay or whether a fee can lawfully be passed on. Do not treat the returned amount as permission to surcharge or as a promise that the provider accepts every boundary amount.
If an agreement includes a cap, tier, minimum fee, different base, separately rounded addition or currency conversion, the supported additive model may be insufficient. Entering an average percentage is an assumption for illustration, not a reconstruction of those terms.
A monthly target is a different problem
The general calculator's monthly mode estimates costs from count, average ticket and recurring cost. It is not a monthly reverse calculator. Individual transaction rounding and a real ticket-size mix can affect total fees, so dividing a monthly target by an average effective rate does not automatically establish a valid set of payment amounts.
Keep transaction estimates and recurring costs separate in a quote. For reconciliation, use the actual transaction list and statement. For planning, retain the disclosed model, sources and exclusions so another person can understand the estimate.
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