Free read-through calculator for any Amazon series — yours or a competitor's. Type each book's Best Sellers Rank (Kindle Store) or its number of ratings, and see how many book-1 readers carry on.
| Book | BSR (Kindle Store) | Ratings |
|---|
Find both numbers on each book's Amazon page, under “Product details”. Fill one column or both. Skip box sets and novellas — only the main numbered books.
We're building SeriesLens, a free Chrome extension for authors of series and Kindle Unlimited books: read-through, estimated KU income, indie vs. publisher and release pace, shown right on Amazon pages. No 3-search limit. Join the waitlist for early access and launch pricing.
One email when early access opens, plus occasional series-market data. Unsubscribe anytime. Privacy.Rules of thumb from indie-author resources (Kindlepreneur, IngramSpark, ScribeCount): around 50%+ from book 1 to book 2 is healthy for a genre series, 30–50% is average, and under 30% usually means book 1's ending, book 2's cover or blurb, or the price step is losing readers. Kindle Unlimited series often run higher because the next book costs the reader nothing extra. These are anecdotal ranges, not a study — compare series within the same genre.
BSR shows current demand: we turn each rank into estimated daily sales with a power curve (sales ∝ rank−0.9) and compare books. It's sensitive to promos and new releases. Ratings show lifetime readers but book 1 often got extra early reviews, so ratings tend to understate read-through. When both agree, trust the result.
A newer book can outsell book 1 for a while (launch week, a promo, a free or discounted book 1 that isn't counted in paid ranks). Check again in a few weeks.
No. The calculation runs in your browser. We only count anonymous page events (no cookies, no IP stored). See privacy.