Reverse fee calculator
Working backwards from take-home to asking price. Useful for invoices, commissions, and any sale where the number that matters is the one that reaches you.
The gross-up formula
To keep a target amount after a percentage fee, divide the target by one minus the fee rate — and add any fixed per-sale fee to the target before dividing. Charging your target plus the fee percentage undershoots every time, because the fee applies to the grossed-up price, not to your target.
The gap is small on small fees and serious on big ones. To pocket $100 under a 3% payment fee you charge $103.09 — close to the naive guess. To pocket $100 under a 20% marketplace commission you charge $125, while the naive $120 leaves you $4 short. People who price commissions naively lose that slice on every single job.
Questions
Why not just add the fee percentage to my target?
Because the platform charges its percentage on the final price, which is bigger than your target. Adding the percentage to the target applies it to too small a base, so you always come up short — by more, the higher the fee.
Does this work for taxes too?
Mechanically the gross-up formula is the same for anything charged as a percentage of the total. But tax situations have their own rules about what base gets taxed, so treat this as arithmetic, not tax advice.
What if there are two separate fees?
If both are percentages of the final price you can add the percentages together and enter the sum. Add any per-sale fixed amounts into the fixed fee field.