Selling on Marketplaces: Real Margin After Fees, Ads and Returns

«I have around 900 listings across three marketplaces. Sales come to ₴1,600,000 a month. And at month-end I hold eighty thousand — which I need for the next purchase order. More orders, a bigger warehouse, and the same money I had two years ago» — that's how Andrii, a marketplace seller, opened our conversation.

Sound familiar? Order notifications pour in all day, the courier collects boxes every morning, the seller dashboard shows a nice green curve. It looks like a growing business. Yet when you sit down to count what's actually yours, the number is embarrassing.

The trouble is that marketplace selling gets measured by turnover and «average markup.» Sold for ₴900, bought for ₴600 — «made ₴300.» That the marketplace took ₴135 in commission out of that ₴300, that in-platform advertising ate ₴60, that packaging and delivery took ₴25, and that every seventh item came back — none of that sticks in your head.

This article is about breaking a marketplace business down into individual products: what actually remains from each SKU after every deduction, and how fast the money you put into stock comes back. Because here profit isn't lost in one big chunk, it's lost in a dozen small percentages.

The Founder's Path: From One Category to 900 Listings

Andrii started with homeware: he brought in a batch of small items, listed them, and sold through in a month. Everything was transparent — one purchase, one price, one invoice.

Then it spread sideways: kitchen, textiles, tools, pet supplies, seasonal lines. More categories meant more orders, more suppliers, more listings. Three years on: 900 active SKUs, three platforms, a rented warehouse, two pickers and a support manager.

And somewhere around the three hundredth listing, «bought for 600, sold for 900» arithmetic stopped meaning anything. Plenty of stock, plenty of sales, and never enough money for the next purchase order. Andrii had exports from the seller dashboards, a purchasing spreadsheet and a bank app. Three sources with the profit vanishing somewhere between them.

«I was sure I was working on a 50% markup. When we counted everything the platform withholds, 11% was left — and on some items it was a straight loss.»

How Money Actually Works in Marketplace Selling

Before we get to what Andrii changed, let's break down what a seller's profit is made of. Because this is exactly where the money that «disappears» gets lost.

The Price on the Listing Isn't Your Money

Between the number on the product page and the sum that reaches you sits a long chain of deductions. Let's count one item honestly.

Sale ₴900. Cost of goods ₴600. Platform commission at 15% — ₴135. In-platform advertising (so the listing gets seen at all) — roughly ₴60 per sale. Packaging ₴15. The delivery you subsidise — ₴20. Processing and handling — ₴10. That leaves ₴60 out of a ₴300 «markup.» And that's before warehouse rent, wages and taxes.

Now add returns: if every seventh item isn't collected or comes back, its delivery both ways, packaging and handling also land on your margin. Instead of ₴60, about ₴35 remains. That's precisely how a million in turnover turns into eighty thousand in hand.

Commission and Advertising: Two Different Things That Get Merged

Commission is fixed and predictable: you know the rate for your category in advance. In-platform advertising is a different story entirely. It works as an auction: the more sellers in a category, the higher the bid. And it creeps up quietly, because everyone raises their bid to stay off page two.

The most common mistake here is looking at advertising as one monthly total. You see «we spent ₴96,000 on ads» and miss that two thirds of it went to three categories where the margin was thinnest to begin with. Advertising has to be allocated by product group — otherwise it quietly eats the weakest lines.

We lifted sales by 40% and couldn't work out why there was less money. The whole difference had gone into ad bids.

Returns and Uncollected Parcels: Two Deliveries for Zero Revenue

A return on a marketplace isn't simply a lost sale. It's a lost sale plus two deliveries, plus packaging, plus the picker's time, plus an item that comes back in a battered box and no longer looks new.

A single product with a 25% return rate can eat the margin of an entire category. So that figure needs to be known per listing: it often turns out the problem sits in one or two cards with a vague description or a wrong size chart. We covered the mechanics of margin leaking in ecommerce separately — where margin leaks away in online retail.

Marketplace Promotions: A Discount You Never Agreed To

Platforms love automatic promotions: «your products are taking part in the sale.» You can opt out, but the listing loses visibility, so most sellers go along with it.

And this is where the quietest loss happens: the discount comes out of your margin while commission is charged on the sale price. An item that yielded ₴60 net goes negative under a 15% promotional discount. Sales are up, the dashboard is green, the money disappears. We wrote about that effect separately — how to spot a promotion going negative before month-end.

Cash Frozen in Stock

Every SKU in the warehouse is your money lying there, waiting. While an item turns over in a month, that's healthy working capital. When it sits for six months, it's frozen cash you're also paying to store.

Out of 900 listings, roughly a hundred usually make most of the turnover, while a tail of several hundred SKUs exists «just in case.» That tail is exactly where the money you never have for restocking your best sellers is sitting. It's the same classic: profit on paper while the cash is stuck in stock.

Delayed Payouts: A Cash Gap on a Schedule

Marketplaces don't transfer money immediately: usually once a week or twice a month, with deductions for the previous period on top. Meanwhile you pay suppliers in advance, often fully prepaid — and for imports, in foreign currency.

So a gap appears: the goods are sold, the money arrives in two weeks, and the purchase order has to go out now so you don't lose your ranking. Without a payment calendar that gap feels like a surprise every time, even though it's entirely predictable.

Life Before Finmap

Before he put things in order, Andrii lived roughly like this. He recognises these lines himself — and you might too.

• «Turnover grows and there's never enough for the next purchase order. Where it goes, I can't tell.»
• «Which listing is genuinely profitable — I couldn't say. I count by overall markup.»
• «Advertising eats a lot, but where exactly it fails to pay back, I can't see.»
• «The warehouse is full of stock that once looked promising.»
• «Payouts arrive late, and every time it collides with the date I owe a supplier.»

Every one of these lines is about the same thing: the business is measured by turnover and average markup instead of net margin per SKU. The moment you break the numbers apart, the picture becomes almost uncomfortably clear.

How Andrii Put Things in Order

The turning point was mundane: a supplier offered a great price on a fast-moving line and there was no cash to buy it — while ₴2.4 million of stock sat in the warehouse. Andrii sat down and realised he wasn't poor, his money was simply parked in slow-moving SKUs. What he needed wasn't «more sales,» it was order in the finances, so he could see where money goes every day.

That's how he came to Finmap. The brief was simple: see net margin by product group after every deduction, know how much cash sits in stock, and plan purchases around the payout schedule. Setting it up took a couple of evenings.

• Bank integration and auto-import. Marketplace payouts and supplier payments pull in automatically — nothing to key in by hand.
• Every product group is its own line of business. Sales, commissions, advertising, delivery and returns attach to a specific category. You see net margin, not «average markup.»
• Commissions and advertising as separate categories. It becomes obvious which platform and which category eat the most.
• Stock as frozen cash. You can see what the warehouse is worth and which SKUs haven't moved.
• Payment calendar. Marketplace payouts, supplier payments, rent and taxes laid out in advance — the gap is visible before it arrives.

What Andrii particularly liked is that Finmap speaks the owner's language rather than the accountant's: not «trial balance,» but «this category yields 22% net and that one is minus 3%.» And that the AI adviser flags the odd stuff by itself: «in-platform ad spend is up 35% while that category's sales are up 6%.»

It turned out a third of my catalogue was working for the marketplace, not for me.

The Finances Now

In four months with Finmap, Andrii cut his catalogue by nearly a third — and started earning noticeably more on lower turnover. Here's what changed.

How did he get there? He delisted the items that went negative after commission and advertising. He cleared dead stock even at a token margin, freeing more than ₴600,000 for fast-moving categories. He rewrote the descriptions and size charts on the three listings with the highest return rates. And he started checking which promotions he was being enrolled in instead of accepting automatically.

An insight for business owners. On a marketplace, profit hides not in turnover but in net margin after every deduction — and in how fast the money in your stock turns over. Two sellers with identical turnover can differ twofold in profit: one knows the margin of every SKU after commission, advertising and returns, while the other watches markup and enjoys the green charts.

A Few Closing Tips

• Calculate net margin per SKU after commission, advertising, delivery, packaging and returns.
• Allocate advertising by product group — otherwise it quietly eats the weakest lines.
• Track return rates per listing, not for the shop as a whole.
• Check promotion terms: the discount comes out of your margin while commission is charged on the sale price.
• Know how much cash sits in stock and which SKUs haven't moved in three months.
• Plan purchasing around the platform's payout schedule rather than by feel.

Money Doesn't Disappear. You Just Don't See It.

A marketplace seller's money doesn't evaporate. It dissolves into commission percentages, ad bids, return deliveries and dead stock in the warehouse while you watch turnover and order counts. The moment you break it down per SKU, you can see what feeds the business and what merely creates motion.

You don't need more orders. You need to see which product genuinely brings in money after every deduction — and to have the kind of order in your finances where that's visible every day, not guessed at once a year.

Try looking at your catalogue in a new way — and within the first month you'll see which listings feed you and which ones are quietly eating you.