What Is ACOS? Formula, Benchmarks & How to Calculate (2026)
ACOS (advertising cost of sales) is your ad spend as a percentage of the revenue those ads generate. The formula is: ACOS = ad spend ÷ ad revenue × 100%. It's the inverse of ROAS — lower ACOS is better, because it means you spent less to earn the same sales. ACOS is most associated with Amazon Ads, but it applies to any order-attributed advertising.
To turn ACOS into a profit floor, use our break-even ROAS calculator; to work out your cost structure, use the profit calculator.
The formula
ACOS = ad spend ÷ ad revenue × 100%
It's the reciprocal of ROAS: ACOS = 1 ÷ ROAS. A ROAS of 4.0 is the same as a 25% ACOS.
At break-even, ACOS exactly equals your contribution margin — you profit when ACOS is below your margin and lose money when it's above.
Worked example
A campaign spends $200 and brings in $1,000 of revenue. ACOS = 200 ÷ 1,000 × 100% = 20%. As a ROAS that's 1,000 ÷ 200 = 5.0. If your contribution margin is 30%, a 20% ACOS is below 30%, so the campaign is profitable; if ACOS climbed to 40%, you'd be losing money.
ACOS benchmarks (relative to your margin)
| ACOS range | Read |
|---|---|
| Well below your margin | Healthy — consider scaling budget |
| Just below your margin | Profitable but tight, watch conversion |
| Equal to your margin | Break-even, no profit or loss |
| Above your margin | Losing money, optimize or pause |
There's no universal "good ACOS": 15% can lose money on a thin margin, while 50% can still profit on a high-margin product. Always compare ACOS against your own margin.
Frequently asked questions
What is a good ACOS? It depends on your margin, not a fixed number. Any ACOS below your contribution margin is profitable. You can tolerate a higher ACOS while scaling, and should push it lower when optimizing for profit.
What's the difference between ACOS and ROAS? They're two views of the same thing: ACOS is a percentage (spend over revenue), ROAS is a multiple (revenue over spend). ACOS = 1 ÷ ROAS. ACOS frames it as cost; ROAS frames it as return.
Is ACOS the same as TACOS? No. ACOS counts only ad-attributed revenue; TACOS (total ACOS) is ad spend as a percentage of total store revenue including organic sales, used to gauge how dependent you are on ads overall.
How does ACOS map to BEROAS? Break-even ACOS equals your contribution margin, while BEROAS = 1 ÷ margin. For example, a 40% margin means a break-even ACOS of 40% and a BEROAS of 2.5.
To place ACOS inside a full per-product profit model, see the TikTok Shop fees and profit-margin breakdown.
Leads EshopPick's product-research and data desk. Focuses on TikTok Shop US sourcing frameworks, fee-and-profit math, and platform comparisons. Every take is grounded in our weekly real-sales data and Opportunity Score — practical calls, not chart-chasing.