#target ACOS #margin #Amazon Ads #KDP #break-even
How to Set Your Target ACOS by Profit Margin
James Whitfield · July 23, 2026 · 6 min read
Your target ACOS should be set from your profit margin: your break-even ACOS equals your margin, and your target sits below it by however much profit you want to keep per sale. Setting it any other way is guessing. This guide shows the simple math for a KDP book.
Step 1: find your break-even ACOS
Break-even ACOS is the point where the ad costs exactly what you earn from the sale. It equals your profit margin on the book.
- A $4.99 Kindle eBook at 70% royalty earns about $3.49. That is a ~70% margin, so break-even ACOS is ~70%.
- A $12.99 paperback might net ~$3.20 after print. That is a ~25% margin, so break-even ACOS is ~25%.
Step 2: set the target below break-even
Your target ACOS is break-even minus the profit you want to keep. If your eBook breaks even at 70% and you want to keep a third of the price as profit, target somewhere around 45 to 55%.
| Format | Break-even ACOS | Sensible target |
|---|---|---|
| $4.99 Kindle eBook | ~70% | 45-55% |
| $12.99 paperback | ~25% | 15-20% |
Step 3: adjust for your goal
- Maximize profit: target well below break-even.
- Build ranking and momentum: run closer to break-even to buy sales velocity, accepting thin margins for a while.
There is no single correct number; it depends on whether you want profit now or growth. Just make sure you always know your break-even so the target is anchored to reality.
Turn the target into bids
Once you have a target ACOS, it drives every bid decision: raise bids on keywords under target, cut bids on keywords over it. Applying that consistently across a catalog is what Essentia automates.
FAQ
Is a lower target ACOS always better? No. A very low target starves the campaign of volume. The best target is the one that maximizes total profit, which is usually below break-even but not near zero.
Should eBooks and paperbacks have the same target? No. Their margins are very different, so their break-even and target ACOS are different. Never apply one number across formats.
When should I run at break-even ACOS? When you are launching and want sales velocity to help organic ranking. It is an investment in momentum, not a long-term setting.