Storage, prep, etc.
A rough estimate of margin lost to returns.
The formula
Break-even ACOS = (net price − landed cost − fulfillment fee − referral fee − other costs − return allowance) ÷ net price. Break-even CPC = contribution per unit × conversion rate.
- Use the net selling price after discounts and coupons, not the sticker price.
- The referral fee here is a percentage of net price. Check Amazon's Fee Preview for your category and exact figures.
- The return allowance is a rough estimate of margin lost to returns, as a percentage of price. Leave it at 0 to ignore returns.
- ACOS only counts ad spend against ad-attributed sales. This calculator shows what margin is left before advertising enters the picture.
Frequently asked questions
What is break-even ACOS?
Break-even ACOS is roughly the contribution margin available before advertising. A $30 product with $24 in non-ad variable costs leaves $6 for ads and profit combined, a 20% break-even ACOS.
Can a low ACOS still lose money?
Yes. ACOS excludes referral fees, fulfillment, storage, returns and cost of goods. A product that is already unprofitable before advertising can run a low ACOS and still lose money on every sale.
What is the difference between ACOS and TACOS?
ACOS divides ad spend by ad-attributed sales. TACOS divides ad spend by total sales, including organic, which shows how dependent a product is on advertising. Neither says anything about product margin on its own.
Go deeper
- ACOS Is Not Profit: Reading Ads, Margin, and Inventory
A 10% ACOS can be excellent, terrible, or irrelevant depending on margin and stock position. Learn to calculate break-even ACOS instead of chasing one number.
- What's a Good ACOS on Amazon? Not One Number
Real 2026 ACOS benchmarks by category range from 19% for books to 57% for apparel. Chasing one universal target cuts the wrong products and scales others.
- Amazon TACOS vs. ACOS vs. ROAS
ACOS and ROAS measure attributed ad efficiency, while TACOS compares spend to all sales. None reveals net profit alone, so confusing them can mislead you.
- How to Calculate Amazon Profit per SKU
Contribution per unit equals revenue minus COGS, fees, freight, ads, returns, and storage. Learn why two dashboards can show different profit for one SKU.
EcomSanity shows sales and inventory per ASIN side by side, so an ad metric is never read in isolation from the stock behind it.
Get started free