How Many Keywords Should an Amazon Book Ad Campaign Have?
Updated 2026-07-15
Ask five Amazon Ads teachers how many keywords a campaign needs and you'll hear anything from 30 to 1,000. The honest answer: the number matters less than the coverage, because keyword impressions follow a power law — a small fraction of your keywords will get almost all the impressions.
Why most keywords get no impressions
Amazon only shows your ad when a real shopper makes a matching search and your bid wins the auction with adequate relevance. Most niche book searches are rare. So out of 200 keywords, it's normal that 20 get real traffic, 50 get a trickle, and the rest sit at zero.
That's not failure — it's why authors are told to add lots of keywords. You're buying lottery tickets on which search terms turn out to be alive in your niche.
Reasonable starting sizes
Bryan Cohen's popular author-ads training, for instance, is famous for pushing high keyword volume with low bids; other approaches favor tighter lists with careful bids. Both work when paired with regular pruning.
- Testing the waters: 50–100 keywords, one campaign, modest daily budget
- Standard launch: 150–300 keywords across comp titles, authors, and genre phrases
- Aggressive/serial approach: continuous weekly additions of fresh keywords, retiring dead ones
Budget interacts with keyword count
A $5/day budget spread over 1,000 keywords means most will never be tested properly. With small budgets, lean toward fewer, higher-intent keywords (comp titles, exact match). Expand the list as budget grows.
The maintenance loop matters more than the number
Whatever size you start with: check the search term report every week or two, negative-out the losers, promote the winners to exact match, and top up with new keyword ideas. A 150-keyword campaign that gets pruned monthly beats a 1,000-keyword campaign set up once and forgotten.
When you need to top up, our free tool turns a handful of new comp titles into a full set of match-type variants in seconds.