ACoS, TACoS and break-even
ACoS measures ad efficiency on ad-attributed sales only. TACoS divides ad spend by total sales (ads + organic) and is a better measure of overall ad health. Break-even ACoS is the maximum ACoS you can sustain before losing money — for KDP paperback it's typically 25–35%.
Target ACoS by goal
Profit-first goal: target ACoS at 60–80% of break-even. Growth-first goal: spend at break-even to capture sales rank. Launch goal: spend above break-even for 14–30 days to seed reviews and BSR. Choose your phase, then bid accordingly.
How to lower ACoS fast
Negative-match exact and phrase terms that have spent $1+ without a sale. Move converting auto-campaign terms into manual exact campaigns with custom bids. Improve your conversion rate by tightening your book description, A+ content and look-inside sample — higher conversion lowers ACoS more than bid cuts ever can.
Why TACoS matters more long-term
ACoS only reflects paid sales, so it can hide whether ads are stealing from organic. TACoS captures the full picture. A successful KDP product trends TACoS down over time while keeping ACoS stable — meaning organic sales are compounding from the visibility ads created.
Frequently asked questions
Is 50% ACoS bad?
It depends on royalty. For 70% Kindle plans, 50% is roughly break-even. For 60% paperback after print cost, 50% loses money.
What's a good TACoS?
Under 15% is great. Under 10% on an established title indicates strong organic ranking.
Can ACoS be 0%?
Yes — when ad-attributed sales exist with zero spend (rare, usually attribution lag).
Why does my ACoS spike on weekends?
Buyer behavior shifts on weekends; competition for keywords often rises and conversion drops in some genres.