ACoS, short for Advertising Cost of Sales, is the headline efficiency metric in Amazon Ads. It tells you how many rupees of advertising it took to produce one hundred rupees of ad-attributed sales. Every Sponsored Products, Sponsored Brands and Sponsored Display campaign in the Amazon campaign manager shows an ACoS column, and most sellers in India judge campaigns by it first. A lower ACoS means the ads are cheaper relative to the revenue they bring in.
How ACoS is calculated
Amazon defines the formula as: ACoS = (ad spend ÷ ad sales) × 100. Ad sales means only orders Amazon attributes to a click on your ad, within the attribution window (7 days for Sponsored Products, 14 days for Sponsored Brands and Sponsored Display as of September 2026). Organic orders are not counted.
Worked example: a seller of steel water bottles spends ₹18,000 on Sponsored Products in a month and the campaign reports ₹72,000 in attributed sales. ACoS = 18,000 ÷ 72,000 × 100 = 25%. Put another way, every ₹100 of ad-driven revenue cost ₹25 in clicks. ROAS is the same ratio flipped: 72,000 ÷ 18,000 = 4.
What a good ACoS looks like
Amazon's own guidance is that there is no single good number; it depends on category, price point and campaign goal. The useful reference is break-even ACoS, which equals your profit margin after Amazon fees. If the bottle sells for ₹599 and, after referral fee, closing fee, shipping and product cost, ₹180 is left, the margin is 30%. Any ACoS below 30% makes money on the sale itself; above it, the ad is a loss unless it is deliberately buying rank or reviews for a launch. New listings often run above break-even for a few weeks and then settle. Mature listings in competitive Indian categories such as kitchenware or mobile accessories commonly sit between 15% and 30%, but check your own margin before copying anyone else's target.
How to improve ACoS
- Work the search term report. Add converting search terms as exact-match keywords and push wasteful ones into negative keywords.
- Bid by placement. If top of search converts well, raise the placement adjustment; if product pages drain spend, lower bids there.
- Fix the listing before the ads. A poor main image or missing bullet points raises the cost of every click because fewer clicks convert.
- Separate branded and generic keywords. Branded terms usually show a very low ACoS and hide problems in the generic campaigns when mixed together.
- Judge ACoS alongside TACoS. A campaign can show a rising ACoS while total sales and organic rank improve, which is often the right trade.
Blooprint's ex-Flipkart team manages Amazon campaigns to a margin-based ACoS target through our marketplace ads management service. For the full set-up walkthrough, read the Amazon ads guide for India.