Marketplace fees

Why two platforms charging the same percentage do not cost the same

Marketplace fees get quoted as a single percentage often enough that sellers compare them as single percentages. That comparison is usually wrong, and it is wrong in four specific ways. Every calculator in this section exists because one of them applies.

What the percentage is charged on

The fee base matters more than the rate. Several marketplaces apply their commission to the postage you charge as well as the item price. A seller who shifts cost out of the item and into shipping pays the same commission either way, and a seller offering free shipping pays commission on money they never counted as revenue. Two platforms at an identical headline rate diverge the moment one includes postage in the base and the other does not. Each calculator here states its own fee base, because it is the input that most often explains the gap between what a seller expected and what landed.

Whether processing is bundled or charged separately

Some marketplaces quote one number that already contains card processing. Others quote a commission and then deduct processing on top, which adds a percentage plus a fixed amount per order. The fixed component is invisible at high order values and dominant at low ones — it is the reason a platform that looks cheapest on a $200 sale can be the most expensive on a $12 one.

Fixed fees, tiers, and cliffs

Percentage fees scale smoothly. Listing fees, per-order fees and flat-rate commissions below a threshold do not. A platform that charges a flat fee under some price and a percentage above it has a discontinuity at that price, and just below it the seller keeps less in absolute terms than a seller just above. Our reseller comparison marks these cliffs explicitly rather than drawing a smooth curve through them, because the curve would be a lie at exactly the price points low-value resellers actually list at.

Fulfilment priced on the box, not the sale

Fulfilment fees do not care what an item sold for. They are priced on dimensions and weight, which means they are a near-fixed cost per unit against a variable revenue line. The same product in the same box costs the same to ship whether it sells for $15 or $45 — so fulfilment is a margin question, not a fee question, and a size tier boundary can cost more than the commission does. The Amazon calculators model the tier the box actually falls into rather than applying an average.

Which calculator answers which question

Use a single-platform calculator when you already know where you are selling and want the arithmetic for one sale. Use a comparison when the platform is the decision — those pages run the same item through every engine and report where each one wins, including the revenue point at which the answer changes. Use the margin calculator when the fee is settled and the question is what price supports the margin you need.