The most common marketplace failure is not a bad product — it is a seller who does not know their own costs. "I sell at 500, buy at 300, so 200 profit" usually turns into a loss after commission, shipping, returns and tax. Let's build the real math step by step.
The Full List of Deductions
- Category commission — varies by marketplace and category; check current rates in your panel
- Shipping fee — deducted by price tier
- Transaction/service fees — fixed per order
- Return cost — return shipping + repackaging + unsellable items
- VAT — you pay the difference between sales VAT and purchase VAT
- Advertising — buybox/top-rank competition is hard without it
- Packaging + operations
Example: A 500 TL Product
Assumptions: cost 300 TL, commission 20%, shipping deduction 45 TL, return rate 8%, packaging 10 TL.
| Item | Amount |
|---|---|
| Sale price | 500.00 |
| Commission (20%) | -100.00 |
| Shipping | -45.00 |
| Packaging | -10.00 |
| Return allowance | -4.40 |
| Product cost | -300.00 |
| **Pre-tax remainder** | **40.60** |
The real margin dropped to 8% — one fifth of the paper profit. Instead of doing this by hand for every product, enter costs into our profit margin calculator, find the right tag price with the sale price calculator, and handle tax with the VAT calculator.
Marketplace-Specific Notes
Trendyol: commission and shipping tiers can change during campaigns; recalculate margins at the discounted price. Hepsiburada: chasing the buybox on margin-less products is the most common route to selling at a loss. Amazon: with FBA, include fulfillment + storage fees, and long-term storage on slow movers.
Checklist Against Selling at a Loss
- I know the AFTER-commission margin of every product
- I checked my shipping tier against the current table
- I set a return allowance (10%+ electronics, 15%+ apparel is realistic)
- I recalculated margin at campaign prices
- I allocated monthly ad spend per product
Golden Rule
If your after-commission margin is below 15%, that product will not make money at scale. "Great revenue, no profit" is marketplace selling's most insidious trap.