ACOS, often written ACoS, stands for Advertising Cost of Sales. The metric puts advertising costs in relation to the revenue that the advertising platform attributes to those ads. The term comes from Amazon advertising, but the calculation works anywhere a platform reports costs and attributed revenue.
How to calculate ACOS
ACOS = advertising costs ÷ revenue attributed to the ads × 100
Example: a campaign costs EUR 150 a month and the platform attributes EUR 1,000 of revenue to it. ACOS = 150 ÷ 1,000 × 100 = 15%. Of every euro of attributed revenue, 15 cents went into the ads.
Two things are worth checking when you read the figure: whether the platform reports revenue with or without VAT, and over which time window it attributes purchases to an ad. Both change the value without anything having changed in the campaign.
ACOS and ROAS
ROAS is the same calculation the other way round: attributed revenue divided by advertising costs. You can convert directly:
- ROAS = 100 ÷ ACOS in percent
- ACOS in percent = 100 ÷ ROAS
An ACOS of 15% corresponds to a ROAS of around 6.7; a ROAS of 4 corresponds to an ACOS of 25%. Which of the two figures you use is a matter of taste. All that matters is that lower is better for ACOS and higher is better for ROAS.
ACOS and TACOS
ACOS evaluates the ad: it divides only by the revenue the platform attributes to it. TACOS divides the same advertising costs by total revenue, including sales without an ad click. If total revenue in the example is EUR 5,950, TACOS is 150 ÷ 5,950 × 100 = 2.5%, while ACOS shows 15%. ACOS helps you steer individual campaigns; TACOS shows how dependent the business is on advertising.
Break-even ACOS: when advertising starts to cost money
Amazon Ads puts it like this: the break-even ACOS is directly linked to the profit margin. Specifically, it is the ACOS at which the advertising costs use up exactly the contribution margin of a sale:
Break-even ACOS = contribution margin before advertising ÷ selling price × 100
Selling price on the same basis as the revenue in the ACOS, i.e. gross or net, as the platform reports it.
Example with the figures from the contribution margin entry: an item sold for EUR 59.50 gross yields EUR 16.57 of contribution margin without returns. That gives 16.57 ÷ 59.50 × 100 = 27.8%.
Returns lower the threshold. In the monthly example with 100 orders and 20 returns, EUR 1,096 of contribution margin remains before advertising, i.e. EUR 10.96 per order. Because the revenue attributed to an ad usually also includes orders that are sent back later, the break-even ACOS is then 10.96 ÷ 59.50 × 100 = 18.4%. An ACOS of 20% looks fine next to 27.8%, but in this case it costs money.
Below the break-even ACOS there is still contribution margin left after advertising; above it, every attributed sale costs more than it brings in. Where the target lies depends on whether a campaign is meant to make a profit or, for example, to introduce a new item.
ACOS, ROAS and TACOS alongside the contribution margin
In profitkonsole, ACOS and ROAS for OTTO Sponsored Product Ads are shown from the revenue that OTTO attributes to the ads at brand level, and TACOS from your own total revenue, together with the contribution margin per item. Amazon ad spend that Amazon deducts from your payout is picked up automatically from your settlement data, as a separate line in the result of your Amazon account, but without ACOS per campaign. If you pay for Amazon Ads by credit card or invoice, you enter it as an indirect expense. Which Amazon costs belong in the contribution margin before advertising is explained in the guide to Amazon fees.
Source of the definition: Amazon Ads, guide to ACOS (retrieved 17 September 2026). In depth on OTTO advertising: Understanding and attributing OTTO advertising costs →
Contribution margin, not revenue
Every sales channel in one dashboard: marketplace data and your own costs brought together, per item and per channel.