MarginMate – Amazon ROI Calculator

Read-only profit, margin and ROI calculator for Amazon UK, EU and CA product pages. VAT-aware.

Know your profit before you buy. MarginMate adds a small calculator to Amazon product pages so online arbitrage and wholesale sellers can check a deal in seconds, without copying numbers into a spreadsheet. WHAT IT SHOWS • Profit per unit • ROI and margin • Max buy price (the most you can pay a supplier and still break even) • Total Amazon fees and VAT due BUILT FOR UK, EU AND CANADA • Works on Amazon marketplaces in the UK, the EU, Canada and the US • VAT-aware: handles VAT-registered and non-registered sellers, VAT on Amazon fees and VAT-inclusive supplier prices • Warns you when Amazon shows prices converted to another currency, so you never calculate with the wrong numbers HOW IT WORKS 1. Open any Amazon product page. The sale price is filled in automatically. 2. Type your supplier price. 3. Adjust referral %, FBA fee and prep costs once; MarginMate remembers them per marketplace and remembers the buy cost per product. PRIVATE AND SAFE • Read-only: it never clicks, submits or touches Seller Central • No account, no tracking, no analytics • Everything is stored locally in your browser FREE, NO LOOKUP LIMITS The calculator is free with unlimited use. A Pro plan with an unlimited watchlist and spreadsheet export is coming soon; join the waitlist from the extension. Note: MarginMate does not estimate FBA fees automatically yet. Check Amazon's fee pages for each item and enter the fee once. MarginMate is not affiliated with or endorsed by Amazon.