How Much Daily Budget an Author Needs to Test Their First Ads
Short answer: there's no universal figure, but the logic is: decide how much you're willing to "lose" total during the testing phase (2-4 weeks), and divide that by the number of test days. That's your learning budget, not a guarantee of results.
Why think in terms of a "learning budget"
The first weeks of any campaign are for collecting data (which search terms convert, what click-through rate your cover gets), not for immediate profit. Treating that money as the cost of getting that information avoids the frustration of expecting profitability from day one.
Signs you can raise the budget
You've already identified, via automatic targeting, which keywords convert best.
Cost per click isn't burning through the daily budget within the first few hours.
You have at least a few reviews — without them, paid traffic rarely converts well.
Amazon Ads' cost per click varies by category and book competition; there's no fixed rate, so the real budget can only be calibrated by watching your own account's data.Documented variability in the Amazon Advertising auction system, 2026