Net profit per unit, true margin, ROI and your breakeven ACOS — in 30 seconds. Built by a UK seller, because the US-built calculators all fumble VAT.
SellerMatrix tracks true profit across every SKU and emails you a Monday P&L — plus a to-do list ranked by £ impact. Join the early-access list and get the UK FBA fee field-guide.
Net profit per unit = sale price − VAT owed (if registered) − landed product cost − referral fee − FBA fulfilment fee − storage − advertising. Most sellers overestimate margin because a spreadsheet skips at least one of those — usually VAT treatment, storage or ads.
Registered: a sixth of your sale price (20% of the net) is HMRC's, but the VAT Amazon adds to its fees is reclaimable. Not registered: you keep the full sale price, but every Amazon fee costs you 20% more because the VAT on fees isn't reclaimable. Flip the toggle above and watch your margin move — that's why UK sellers can't trust US calculators.
After all fees and ads: 20–30% is healthy private-label territory, 10–20% is workable with volume, under 10% leaves no room for a fee hike or a bad ad week. Launch-stage products deliberately run thinner — stage matters, which is exactly how SellerMatrix sets targets.
Your contribution margin before ads, as a % of price. Spend more than that per sale on ads and the sale loses money. Check yours against stage-based targets with our free ACOS calculator.