Why simply adding the percentage fails
Suppose you want to keep $1,000 after a 20% platform fee. Charging $1,200 creates a $240 deduction, leaving $960. The extra $200 was also subject to the fee, so the target is missed.
The correct gross amount is $1,000 divided by 0.80, which equals $1,250. A 20% deduction from $1,250 is $250, leaving exactly $1,000.
Include fixed charges in the correct place
Payment processors may combine a percentage with a fixed transaction charge. To receive a target amount, add the fixed charge to the target first, then divide by one minus the percentage rate. The general formula is (target net + fixed fee) ÷ (1 − percentage fee).
Fee schedules can vary by country, payment method, currency, account type and cross-border status. Enter the rate shown in the provider terms for the transaction you actually expect rather than relying on an old example.
Decide whether the fee is visible or built into pricing
Some contracts allow a processing charge; other platforms prohibit passing certain fees directly to the customer. Local rules can also control surcharges. Even when you cannot display a separate line item, the cost can still be included when setting the overall price.
For recurring client work, compare fee cost with alternatives such as bank transfer or a lower-cost invoicing method. Consider convenience, payment speed, currency conversion and dispute protection—not the headline percentage alone.
Track the realized rate
After payment, divide the amount actually received by the hours or deliverables supplied. This realized rate exposes fee changes, currency conversion and unpaid scope that the original quote may hide.
Review a few real transactions before updating every price. A calculation is most useful when it is compared with the amounts that actually reached the account.