A seller compares two marketplaces. One charges twelve percent and one charges fifteen. She joins the cheaper one and discovers a payment processing fee, a monthly subscription, a charge on refunded orders and a promotional fee she agreed to without understanding.
The fifteen percent platform would have netted her more.
A worked example
Say an item sells for 60 with 4 postage charged to the buyer, so 64 collected.
Platform commission at 12 percent on the full 64 is 7.68.
Payment processing at 2.9 percent plus 0.30 is 2.16.
A monthly subscription of 25 spread across forty sales is 0.63 per order.
Actual postage costs the seller 3.60, and packaging 0.40.
The seller receives 64, pays 7.68 plus 2.16 plus 0.63 plus 4.00 in fulfilment, leaving 49.53 against an item priced at 60.
That is an effective cost of selling of around 17 percent on the item price, against a headline commission of 12.
Now add a refund. If that order is refunded and the commission is not returned, the seller has lost the fees on a sale that produced nothing, which is why refund handling matters as much as the rate.
Show the break-even on postage
Sellers routinely absorb postage without working out what it does to a margin already carrying commission and processing fees. Showing how a free delivery threshold interacts with the fee structure, and at what order value it stops costing the seller money, is the single most useful piece of arithmetic a marketplace can publish for the people selling on it.
Publish the full picture
A worked example on the seller page, with the fees itemised. Sellers who understand this stay. Sellers who discover it in month two leave and tell others why.
State what commission applies to
Item price only, or item price plus postage, plus any gift wrapping. Charging commission on postage is common and is the detail that surprises people most.
Explain refund and cancellation treatment
Whether commission is returned on a refund, whether processing fees are, and what happens on a partial refund. This is where sellers feel most aggrieved.
Be clear about promotional fees
Sponsored placement, campaign participation and whether any are opt-out rather than opt-in. Sellers who find a fee they did not knowingly agree to lose trust permanently.
Publish category differences
Where commission varies by category, publish the table. Sellers listing across categories cannot plan otherwise.
Explain the subscription decision
Where a paid tier reduces commission, show the break-even volume. Helping a seller choose the cheaper option for their volume builds the relationship.
Payouts are the other half
When money actually reaches a seller, and what can hold it, matters as much as what is deducted from it, and the onboarding friction around both is described in seller onboarding questions that slow marketplace growth.
Trust affects what sellers accept
It is covered in trust and safety questions marketplace users ask.
Fee transparency matters on both sides
It is the point of what buyers ask about fees and why it matters and proactive support answering questions before customers ask.
Getting started
Publish a full worked example, what commission applies to and how refunds are treated, then answer fee questions at any hour. SpideyChat for marketplaces answers from your published pages, our plans are on the pricing page, and the chatbot ROI calculator works through the numbers.