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What is ACOS on Amazon, and what should yours be?

ACOS (Advertising Cost of Sales) tells you how much you pay in ads for every dollar of sales those ads produce. It is the first number most Amazon sellers look at, and the easiest one to misread. This guide gives the formula, the numbers that matter next to it, and a practical way to decide what ACOS is acceptable for each product.

Updated 2026-10-25

The ACOS formula

ACOS = ad spend / sales attributed to those ads x 100. If you spend $30 on Sponsored Products ads and Amazon attributes $120 of sales to them, your ACOS is 25%.

ACOS only counts the sales Amazon attributes to the ad click (within the attribution window). It says nothing about the rest of your sales, and nothing about what the product costs you.

ACOS, TACoS and ROAS: what each one answers

  • ACOS: how efficient are my ads at turning spend into attributed sales? Lower is better, but only relative to margin.
  • TACoS (Total Advertising Cost of Sales): ad spend / total sales (ads plus organic). It shows whether advertising is lifting the whole business or just replacing organic sales. Falling TACoS with steady sales usually means organic rank is improving.
  • ROAS (Return on Ad Spend): attributed sales / ad spend, the inverse of ACOS. A 25% ACOS is a ROAS of 4.

Find your break-even ACOS first

There is no universal good ACOS. The number that matters is your break-even ACOS: the profit margin you have before advertising. If a product sells for $40 and, after Amazon fees, shipping and product cost, you keep $14, your margin before ads is 35%. At a 35% ACOS you break even on every ad sale; at 20% you keep 15 points of margin.

Launch campaigns can run above break-even on purpose to build reviews and rank. A mature product running above break-even for months is losing money on every ad sale, however good the ROAS looks.

How to lower ACOS without losing sales

  • Add negative keywords from the search term report: terms that spend and never convert are the fastest saving.
  • Lower bids on keywords whose ACOS is above break-even and raise bids where it is well below, in small steps and with enough clicks to judge (a keyword with two clicks has not told you anything yet).
  • Fix the listing before the bid. Conversion rate is the other half of ACOS: a better main image, title and price lower ACOS at every bid.
  • Separate campaigns by intent (branded, competitor, generic, auto discovery) so one weak group does not hide inside a healthy average.
  • Use dayparting and budget caps for hours or days that consistently convert worse, based on your own data.
  • Review placement reports: top-of-search often converts better, but costs more per click.

What ACOS cannot tell you

A 15% ACOS on a product with thin margin can lose money, and a 40% ACOS on a high-margin product can be very profitable. ACOS also ignores returns, storage fees, coupons and the cost of goods. Track profit per SKU, not ACOS alone.

Quick answers

What is a good ACOS on Amazon?

One below your break-even ACOS, which is your margin before advertising. Many categories sit between 15% and 35%, but your own fees and costs decide it.

What is the difference between ACOS and TACoS?

ACOS divides ad spend by sales attributed to ads. TACoS divides ad spend by total sales, including organic, so it shows how much of the whole business advertising costs.

Is a high ACOS always bad?

No. During a launch you may accept a higher ACOS to gain rank and reviews. For a mature product, a sustained ACOS above break-even loses money.

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