Breakeven ACOS Calculator
Know how much you can spend on ads and still make money on every sale. See your number on a clear gauge, and test new price points before you touch your live listing. Free, no signup.
Your book
For the most accurate number, copy your exact royalty per sale from your KDP dashboard (Reports → Royalties) — it already accounts for printing and delivery. Don't know it yet? The Royalty Calculator estimates it from your book specs.
Breakeven ACOS is a bidding guardrail, not your real profit. It doesn't account for Kindle Unlimited read-through, returns, or series read-through, so true profitability is usually higher than this single number suggests. Use it to cap your bids, not to judge whether a book makes money.
The color bands are rules of thumb, not verdicts — the right ACOS depends on your niche and cost-per-click.
Test list prices for your book
Set your book's specs once, then try different list prices and watch the breakeven ACOS shift before you touch your live listing. The royalty is computed from KDP's printing cost, so raising the price lifts both your royalty and your ad headroom.
Printing cost: $3.40 per copy
Frequently asked questions
What is ACOS and why does breakeven matter?
ACOS (Advertising Cost of Sale) is what percentage of your sale price you pay in ad spend. Breakeven ACOS is the maximum you can pay before each sale loses money. If your breakeven is 40%, you can bid up to 40 cents per dollar of sale and still make a profit.
Why does the gauge change color?
The bands are rules of thumb, not hard verdicts. Green (35% and above) means comfortable margin for ad spend. Yellow (30% to just under 35%) means margin is tight; bid carefully. Red (under 30%) means low margin for most ad strategies. What counts as a good ACOS really depends on your niche and cost-per-click, so treat these as a starting point.
How do I use this to set bid strategy?
Aim to keep your average ACOS in your Amazon Ads dashboard below your breakeven ACOS. If your breakeven is 40% and your campaign is running at 30% ACOS, you're profitable and can bid more aggressively. At 50% ACOS, you're losing money on every sale.
Where do I find my royalty per sale?
The most accurate source is your KDP dashboard: go to Reports → Royalties and read the per-sale royalty for your book. That figure already accounts for printing and delivery costs. If your book is not published yet, our free Royalty Calculator estimates it from your trim size, page count, ink type, marketplace, and list price for both the 60% and 40% tiers.
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