What this calculator does
It models the two fees that decide whether an FBA product works: the referral fee (a percentage of the sale price, set by category) and the FBA fulfilment fee (a flat charge based on unit size and weight). Subtract both plus your landed cost and inbound freight, and you get real profit per unit — the number that matters, not the headline price.
The size tier is doing the work
Amazon prices fulfilment by size tier. A unit under 15 × 12 × 0.75 inches and 16 oz is small standard and cheap to ship; cross into large standard and the fee rises; go oversize and it jumps again. The calculator classifies your dimensions automatically, so you can test whether shaving half an inch off a box moves the product into a cheaper tier.
What sellers get wrong
- Forgetting inbound freight — it silently eats 2–5 points of margin
- Pricing to a 30% margin and discovering returns and storage fees take another 8%
- Ignoring the low-price FBA threshold: small, cheap items often pay proportionally more
- Assuming the referral percentage is the same in every category
How accurate is this?
Fees follow the published 2025 US rate card with a simplified size-tier model. Amazon adjusts fees annually and applies category-specific rules (apparel, dangerous goods, oversize tiers). Use this for pricing decisions and sanity checks; confirm the exact number in Seller Central's revenue calculator before committing to a large inventory buy.
Frequently Asked Questions
What percentage does Amazon take?
Referral fees run 8–20% by category, with 15% the most common. This calculator applies the rate you select to the full sale price.
Are FBA fees charged per unit?
Yes — fulfilment is per unit shipped, plus monthly storage on what sits in the warehouse.
Why is my FBA fee higher than expected?
Usually size tier: a box a fraction over a dimension threshold moves into the next tier and adds dollars, not cents.
Assumptions & disclaimer
Results are estimates for planning. Fee schedules, tax brackets and deduction limits change; confirm current figures with the marketplace, the IRS or a qualified accountant before making decisions. Nothing here is financial, tax or legal advice.
Privacy & Your Data
BizCalcTool runs entirely in your browser. The figures you enter are never uploaded, stored or shared — there is no backend to send them to.