I pay a platform commission and a payment gateway fee; do I add the two percentages in one field?

Why adding them works

When every fee is a percentage of the same number, the selling price, their total is one percentage of that same number. 12% of price plus 2.5% of price is 14.5% of price. The percentage fee field in the Selling-price calculator takes a single figure, so that is where every rate with the same base is combined.

Forgetting the gateway here means pricing about 3.93 too low per piece, and that comes out of your margin on every order.

When a straight sum is not exact

Some fees are not charged on the selling price. A gateway may, for example, take its rate on the payout the platform sends you after commission, not on the original price. The gateway's real cost is then less than 2.5% of the price.

1. Convert the rate to a selling-price base: 2.5% of 88% of the price (what remains after the 12% commission) is 2.2% of the price.
2. Add: 12% + 2.2% = 14.2%.
3. Enter 14.2 as the percentage fee: price 106.38 instead of 106.87.

The gap is small here, and the straight sum errs in your favour because it slightly overstates the fees. If you want simplicity, adding directly is safe. If you want precision, convert the rate as shown.

How to tell each rate's base

• Read one order statement: divide each fee amount by the selling price. If you get the contract rate, its base is the selling price.
• If it comes out slightly lower, it is probably charged on a smaller amount, such as the payout after commission.
• If it comes out higher, it may be charged on price plus shipping or tax. That is a different case: add the difference as a fixed amount.

After pricing, check the margin of a real order by adding every deduction to cost in the Profit margin calculator.