That range gets repeated in every ads guide, but it's borrowed from private-label sellers. On KDP, your real break-even depends on your royalty, and it moves a long way by format. Find yours below.
Why this isn't the number in your ads console. ACOS compares your ad spend to the list price Amazon credits the ad with, not what actually lands in your account. For KDP specifically, that gap is real: a 70%-tier ebook, a 35%-tier ebook, and a paperback of the exact same book each have a genuinely different break-even point, because royalty math differs by format.
This is a ceiling, not a target. Bidding right up to your break-even ACOS means zero margin on every ad-driven sale. Most authors should aim meaningfully below it, and lean on organic and read-through sales for the rest of the margin.
Tracking this by hand across a growing catalogue gets old fast. Troven Ads Optimizer calculates break-even per book, per format, per marketplace automatically, then finds and applies the weekly changes that keep your campaigns inside it.
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