Payment Fee Calculator

How to use Payment Fee Calculator

The fee is percentage times gross plus a fixed amount, rounded once under your selected rule. Reverse mode searches exact minor units and verifies the resulting net target rather than trusting an unrounded division.

1. Enter gross amount or target net, percentage fee as fraction, fixed fee, minor-unit decimal places.
2. Choose the stated convention and check the units and supported model.
3. Calculate, inspect the result, then copy or download it.

Good to know

• Plain decimal inputs without exponent notation, amounts up to1 trillion, fraction0≤rate<1 and0–6 minor-unit decimal places. Fee rounding is a user convention; no provider price, tax or settlement rule is assumed.
• Runs locally. Text/JSON fields are capped at30,000 characters; stricter page-specific and numeric-string limits also apply. Numeric inputs are bounded to magnitude1e15 and nonzero magnitude at least1e-100 unless an exact-string mode states otherwise. Approximate summaries use12 significant digits; CSV numeric cells retain the complete stored value and potentially formula-like string cells gain a protective apostrophe; unsupported, non-finite or detected underflow states return an error.
• Educational user-assumption arithmetic only. No live prices, laws, tax rules, quotes or financial advice.