Margin After Fees Calculator

Written out

Margin after fees is contribution as a share of price once platform and payment charges are deducted alongside the cost of goods. Written out: (price − cost − platform fee − payment fee) ÷ price.

The reason it deserves its own calculation is that platform fees are charged on the gross including shipping, while cost of goods is not. Netting them into a single margin figure without that distinction produces a number that is wrong by the fee rate times the postage.

The same thing with real figures

A $45 item with $6 of buyer-paid shipping, $18 of cost, a 12% marketplace fee and payment processing at 2.9% plus 30 cents.

Gross is $51. Marketplace fee is 12% of $51 = $6.12. Payment processing is $1.78. Cost of goods $18. Contribution before fulfilment is $25.10 on a $51 gross, which is 49.2%.

Calculating the fees on the $45 item price instead gives $5.40 and $1.61, producing $30.99 and 60%, an eleven-point overstatement caused entirely by leaving the shipping out of the fee base.

The catch

It varies by channel for the same product, which means a single margin figure across a multi-channel business is a blend that describes no actual sale. A product at 49% on a marketplace might be 62% on your own site, and range decisions made on the blended figure will be wrong for both.

Fee schedules also change. A margin calculated against last year's platform rates is stale, and platform fee increases are the most common reason a product that was profitable quietly stops being so.

Applying it

Calculate it per channel and keep the channel figures separate. The comparison between them is what tells you where each product belongs and what a channel is actually costing you in margin terms.

Then check it after every platform fee change. The change itself is usually announced as a small percentage; its effect on your margin is that percentage divided by your margin, which is a considerably larger number.

Deciding whether a channel is worth it

A channel taking twelve points of margin looks expensive against a direct site taking three. The comparison is incomplete, because the direct site has to find its own customers and the marketplace supplies them.

The honest version compares margin after fees on the marketplace against margin after fees and acquisition cost on the direct site. If direct customers cost $18 to acquire on a $45 order, that is 40% of the price, considerably more than the marketplace's twelve points.

The calculation usually favours marketplaces for customer acquisition and direct for repeat purchase, which is why the strongest position is generally both: acquire where it is cheap and retain where the margin is. What it does not favour is abandoning a marketplace because its fee looks high in isolation, which is a decision made by comparing one cost against no cost at all.

A related point: some platforms charge on the pre-discount price and some on the post-discount price. On a promotion-heavy channel that difference can be a full point of margin, and it is the kind of detail that only becomes visible when a fee statement is reconciled line by line against expectations.

Doing that reconciliation once per channel, rather than trusting the published schedule, is what turns a fee estimate into a fee figure.