The real cost of Amazon fees (and how to calculate true profit)

Amazon makes money on every sale through referral fees and, for FBA sellers, fulfillment and storage. If you only subtract COGS from sell price, you are overstating profit by 20–40% on many categories. Here is how each fee works and how to bake them into a true profit number.

Referral fees: the percentage Amazon takes on every sale

Referral fees are a percentage of the item price (excluding tax in most cases). Category matters: consumer electronics might be 8%, while clothing can be 17%. Always confirm in Seller Central for your exact category — the difference between 8% and 15% on a £30 item is £2.10 per unit, which destroys thin arbitrage deals.

FBA fulfillment: pick, pack, and ship

FBA fees depend on product dimensions and weight, not just weight alone. A small standard parcel costs far less than oversize. Seasonal storage fees and long-term storage can also apply if inventory sits. When evaluating a product, use the fee tier that matches the actual package — not the cheapest tier you hope for.

Inbound shipping: the fee sellers forget

Getting product from your supplier to Amazon’s warehouse has a per-unit cost — pallet freight divided by units, or per-carton shipping. Spread that across every unit in the shipment. Skipping inbound cost is the fastest way to think a wholesale deal works when it does not.

The true profit formula

• True net profit = sell price − COGS − inbound − referral − FBA − other (packaging, prep, ads per unit)
• True margin % = net profit ÷ sell price × 100
• True ROI % = net profit ÷ (COGS + inbound) × 100

Parseflow applies these inputs automatically from the listing plus your buy price — so you see true profit without rebuilding a spreadsheet for every ASIN. Use the Amazon profit calculator for URL-based analysis, or the manual FBA calculator when you want full control over every field.