
Break-even ACOS is the exact point where an Amazon ad stops costing you money. Here is the formula, worked examples for ebooks and paperbacks, and why comparing ACOS to your list price is the mistake quietly draining your budget.

Amazon ads have no minimum spend and no fixed price — you pay per click, at auction. Here is what book clicks typically cost, what a $5, $10 and $20 daily budget realistically buys, how to size a budget from your royalty instead of a round number, and when raising the budget is the wrong move.

The same book can be profitable in the US and lose money in Germany once ad VAT, withholding tax, and currency conversion are counted. Here is why you can't just add up numbers from different dashboards — and what a consolidated, tax-aware P&L should look like.

When a Kindle Unlimited reader clicks your ad and borrows your book, Amazon records the spend but zero revenue — so your ACOS looks awful even when you made money. Here is how KENP page-read royalties change the math, and how TACOS folds them into the royalties your ads actually generated.

An account-level ACOS hides the losing titles your winners are subsidising. Here is how to calculate net profit per book, the costs authors forget, and a simple framework for deciding what to scale, fix, or pause.

Screenshots of five-figure months tell you nothing about what KDP realistically pays. Here is the honest math: what one book earns at realistic sales volumes, why gross royalty screenshots hide the ad spend behind them, and the three levers that actually move author income.