ACOS measures Amazon ad efficiency: ad spend divided by ad revenue, as a percentage. Lower is more efficient.
ACOS (Advertising Cost of Sales) is the core efficiency metric for Amazon advertising. It answers one question: for every dollar of sales my ads generated, how much did I spend on those ads?
Formula: ACOS = (ad spend ÷ ad-attributed sales) × 100
If you spent $25 on ads and they produced $100 in sales, your ACOS is 25%. An ACOS of 100% means you spent exactly as much as you earned — every point above your profit margin is money lost.
What's a good ACOS? It depends entirely on your margin. If your product margin (after COGS and Amazon fees) is 30%, then 30% ACOS is your break-even point. Sellers commonly target 15–30% for profitability, but a launch campaign may deliberately run a higher ACOS to build rank.
ACOS is the inverse of ROAS: ACOS 25% = ROAS 4.0. Amazon's console reports ACOS; most cross-channel tools report ROAS.
Try our free ACOS calculator, or get a free audit that shows your real ACOS picture across every campaign.
Connect your Amazon Ads account and get a free audit — wasted spend, untapped winners, and your true ACOS picture. No credit card.
Get Your Free Audit →