Use Amazon's calculator first. Genuinely.
Amazon publishes the live referral and FBA fee tables, and its own calculator reads from them. Nothing on this site copies those tables, because a copy goes stale silently and you would price a product on it. Get your fees from the source: the US calculator or the UK one, which Amazon runs separately because the fee schedule and VAT rules differ.
What it actually calculates
You give it dimensions, weight, category and price — or just an ASIN — and it returns referral fees, fulfilment costs, storage, net profit per unit and margin, with FBA compared against fulfilling yourself. That is a real, useful answer, and it is free without an account.
Where it stops
1. It does not model advertising at all
Not ACOS, not ad spend, not cost-per-click. Its inputs and outputs are fees and margin. So it will tell a seller their unit clears £6 of profit and say nothing about whether they can afford the £1.40 click it takes to sell one.
That is not an oversight on Amazon's part. Amazon has no commercial reason to build the tool that tells you to spend less on Amazon Ads.
2. For UK sellers, it does not take VAT off your price
It accounts for digital services tax inside referral fees, and referral fees are charged on the total sales price. But your £30 sale price is not £30 of revenue if you are VAT registered — at the 20% standard rate you keep £25.00 and remit £5.00 (GOV.UK rates: 20% standard, 5% reduced, 0% zero-rated).
A UK margin read straight off the tool is overstated by exactly that amount. On a thin product that is the difference between a viable ASIN and one that quietly loses money on every advertised sale.
The number that actually decides your bid
Margin is not the decision. The decision is what you can pay for a click, because that is the unit a bid is set in. Two products with identical margins have completely different maximum bids if one converts at 12% and the other at 4%.
That chain — margin, then break-even ACOS, then max CPC — is the part no fee calculator does. Ours does only that part:
- Amazon revenue calculator (UK) — subtracts VAT, then gives break-even ACOS and max CPC
- Amazon revenue calculator (US) — same, without the VAT step
- Break-even ACOS calculator — if you already know your margin
The rest of Amazon's free toolkit
- Fee and pricing estimator — compares fulfilment methods
- Product Opportunity Explorer — units sold and average price by niche; needs a selling account
- Inventory tools — stock monitoring inside Seller Central
All free, all worth using. None of them touches what a click is worth to you.