Free tool · advertising cost of sale and break-even ACOS

Free ACOS calculator

ACOS (advertising cost of sale) is the share of ad-driven sales that went on the ads: ad spend divided by ad sales, times 100. This free ACOS calculator works it out, shows the matching ROAS, and when you add your profit margin it shows your break-even ACOS, so you can see whether the ads make money once they are paid for.

By the Dolphin Analytics team · Last updated · ACOS as defined in Amazon Ads' ACOS guide

What the ads cost in the date range.
Sales credited to the ads in the same date range.
Margin on what you sell, after product, delivery and marketplace fees, before ad costs. Adds break-even ACOS.
Your ACOS 25.00% £500.00 ÷ £2,000.00 × 100 = 25.00%
From the same numbers
Same result as ROAS
4.00x
Break-even ACOS
40.00%
Profit after ad spend
£300.00
At or under break-even: the margin on these sales covers the ad spend.

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What is ACOS?

ACOS (advertising cost of sale) is ad spend divided by the sales those ads brought in, shown as a percentage. Amazon Ads reports it for sponsored ads. £500 of spend that brings in £2,000 of sales is a 25% ACOS: a quarter of every pound of ad-driven sales went on the ads. Lower is better.

How do ACOS and ROAS relate?

They are the same ratio turned upside down. ACOS = 100 ÷ ROAS, and ROAS = 100 ÷ ACOS. Amazon Ads reports ACOS; Google Ads and Meta Ads report ROAS.

ROASSumACOS
2x100 ÷ 250.00%
2.5x100 ÷ 2.540.00%
4x100 ÷ 425.00%
5x100 ÷ 520.00%
8x100 ÷ 812.50%

What is break-even ACOS?

Break-even ACOS is the ACOS at which the profit margin on ad-driven sales exactly pays for the ads, and it equals your profit margin. At a 40% margin, an ACOS under 40% leaves profit after ad costs and an ACOS over 40% loses money on those sales.

Is ACOS the same as TACOS?

No. TACOS (total advertising cost of sale) divides ad spend by all sales, including sales that did not come from ads. ACOS shows how efficient the ads are; TACOS shows how much the business as a whole leans on advertising.

Frequently asked questions

Is this ACOS calculator free?

Yes. The Dolphin Analytics ACOS calculator is free, needs no sign-up and runs in your browser, so the numbers you enter never leave your device.

What is a good ACOS?

A good ACOS is one under your break-even ACOS, which equals your profit margin. A 25% ACOS makes money at a 40% margin and loses money at a 20% margin.

How do I convert ACOS to ROAS?

Divide 100 by the ACOS. A 25% ACOS is a 4x ROAS, and a 40% ACOS is a 2.5x ROAS. The calculator shows both from the same spend and sales.

Which sales figure should I use?

Use the sales the ads drove in the same date range as the spend. On Amazon that is the attributed sales figure in the campaign report. For Google or Meta ads, check the platform figure against your shop or GA4, because each platform claims sales under its own attribution rules.

Does ACOS include product costs?

No. ACOS uses sales, not profit. That is why break-even ACOS matters: it builds your margin into the target.

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