About this calculator

This calculator estimates per-unit net profit, net margin, ROI and break-even ACOS for Amazon FBA and FBM sellers. Enter your sale price, product cost, referral fee, FBA fulfillment fee, inbound shipping, storage, ad spend ratio, return rate and any other variable cost — results update live as you type.

How to use

  1. Pick a scenario preset (standard / apparel / oversized) to load reasonable defaults.
  2. Replace each field with your real numbers from your seller back office or P&L.
  3. Read the four result tiles to spot which lever (cost, ads, returns) hurts margin most.
  4. Compare break-even ACOS with your campaign ACOS to size advertising headroom.

Field reference

Sale Price
Listed price minus on-page promotions; do not include sales tax.
Product Cost
Landed product cost at your home factory or supplier.
Referral Fee %
Amazon category referral, typically 8–17% (15% for most categories).
FBA Fulfillment Fee
Per-unit pick & pack fee from the latest FBA fee schedule.
Inbound Shipping
Per-unit cost to ship from your factory to FBA receive center.
Storage Fee / Unit
Monthly storage prorated to a single unit by inventory turn.
Ad Cost % (ACOS)
Ad spend divided by ad-attributed sales — pull from Campaign Manager.
Return Rate %
Returns / orders. Apparel and shoes can hit 10–20%.
Other Variable Cost
Coupons, free units, samples, FX losses prorated per unit.

FAQ

What is a healthy Amazon net margin?

For most resellers, 10–20% net margin is sustainable. Below 5% you are usually one fee change or PPC bump from losses; above 25% means you should expect copycat pressure.

How is break-even ACOS computed?

Break-even ACOS = (price − all non-ad costs) / price. It tells you the maximum ad share your unit economics can absorb before profit becomes zero.

Why does my ROI differ from the formula on other sites?

We define unit ROI as net profit / total unit cost, including ad spend and returns. Some calculators only divide by product cost, which inflates ROI artificially.

Should I include long-term storage and aged inventory surcharges?

For SKU-level pricing, yes — fold them into the per-unit storage field. For health checks, you can ignore them initially and add a sensitivity pass.

How often should I rerun this calculator?

After every Amazon fee update, every supplier price change, and at minimum once a quarter for active SKUs.

Can I use this for international marketplaces?

Yes. Convert all costs and price into a single currency (USD by default). For the EU, remember VAT is a price component, not a fee — adjust the price field accordingly.

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