Marketplace fee calculator
Net proceeds are the total the customer pays, less a percentage fee, a fixed fee and any listing charges, less your own costs. At 10% plus 0.30 on a 50 sale, fees are 5.30 and the effective rate is 10.6%.
How to compare platform fees
The fixed fee is what makes low-value sales uneconomic, and the effective rate row exposes it. A 0.30 fixed fee is 0.6% of a 50 order and 6% of a 5 order, so a platform with a low percentage and a high fixed fee is expensive for small baskets and cheap for large ones. That single fact drives minimum order values, bundle pricing and free-shipping thresholds far more than the headline commission does.
Questions
Total fees divided by the total the customer paid. It is always higher than the headline percentage because of the fixed fee.
The fixed fee does not shrink. On a 5 order a 0.30 fee is 6%; on a 50 order it is 0.6%.
If the fixed fee plus picking cost eats the margin on small baskets, yes. This tool shows where that line falls.
Almost always, because they apply to the amount charged. So do most marketplace commissions.
It depends on your average order value. Run the same sale through two presets and compare the effective rate.