ACOS
Advertising Cost of Sale
Ad spend divided by ad-attributed sales, expressed as a percentage. A measure of advertising efficiency.
ACOS = advertising spend ÷ ad-attributed sales × 100. For example, $100 spend and $400 ad-attributed sales gives 25% ACOS. Use the same currency, scope and date window for both inputs.
ACOS is not net profit. It excludes product costs and fees, and its denominator is ad-attributed sales rather than all business sales. Compare it with Break-even ACOS and the goal you chose. A low ACOS on a tiny amount of traffic does not automatically mean the account is growing profitably.
With zero ad-attributed sales, ACOS is undefined; show spend and zero sales rather than treating it as 0%. With positive sales and spend, ROAS is its reciprocal: 25% ACOS equals 4× ROAS. TACOS uses total sales instead, when that data is available.
AutoPPC uses saved ACOS targets in its Sponsored Products decision rules. Read the bidding guide for the calculations and safeguards, or the audit checklist for the wider account review.