Book 1 acquires readers — read-through decides how many pay through
Series value per reader who bought book one is the business. At $4.99 Kindle 70% is $3.49 per book, so a three-book thriller where book one sold 240, book two 144, and book three 86 in the last 30 days has read-through 60% book1→2 and 60% 2→3. A reader who bought book one is worth $3.49 plus 60% of $3.49 for book two plus 36% of $3.49 for book three — $7.48 across the series. Book one price decides how many enter; read-through decides how many pay through to the end, and series monthly $839 at that royalty is the business, not the single's $418 from book one alone.
The checker asks sales per volume for the last 30 days — not lifetime — for books one through three, plus the series price that sets royalty. Price is $2.99 to $9.99 for 70% $3.49 at $4.99, outside that window 35% halves the per-book royalty and the series value, so a $0.99 book one at 35% $0.35 per book where read-through is 60% and 60% is $0.74 series value per reader, not $7.48. A $1.99 at 35% $0.70 per book where 60% and 60% is $1.48, still a fraction of the $7.48 where $4.99 holds 70%. Book one at $0.99 or free can still win if it lifts book one sales enough that 60% of a larger base pays more series dollars than 60% of a smaller base at $4.99; that is the lever.
Read-through is next-book sales divided by prior-book sales. Book two 144 divided by book one 240 is 60% 1→2. Book three 86 divided by book two 144 is 60% 2→3. Average read-through 60% is strong. Under 35% 1→2 is fail at this funnel, 35 to 50 thin, 50 plus healthy, 60 plus strong. Book two →3 at 27% is warning leak at 2→3 after a good 1→2, because the third book's opening or the gap between 2 and 3 is the fix, not acquisition. A book three that sells more than book two in the same 30 days without a promo spike is data that includes a boxed set counting as book three or a promo day blended in.
Finished hours, price times platform share, sample windows, and SAY sheets all live elsewhere. A nine-hour thriller at $275 PFH is $2,475 production before the first sale, at $19.99 exclusive $8.00 per sale at 40 sales is $320 per month, the sample 5:00 at 63:00–68:00 is where the hook is heard, and the SAY KAEL-en is how it is said. Read-through is none of those; it is whether the reader who paid for book one paid for book two.
How the series value is built — royalties that compound across volumes
Book one sales is readers who entered the funnel in the last 30 days. Book two sales is readers who bought the next volume in the same window. Book three sales is readers who bought the third. The tool does not blend lifetime; it takes the 30-day per-volume you enter. A duology sets book three to zero; read-through is then book1→2 only and series value is royalty times one plus read-through, with book2→3 at zero.
Price sets royalty per book. At $4.99 70% is $3.49, at $3.99 $2.79, at $9.99 $6.99, below $2.99 35% at $0.99 $0.35 is $0.35, at $1.99 $0.70, at $12.99 outside window 35% at $4.55. The same read-through at $4.99 70% and at $0.99 35% is a ten-fold series value gap at the same 60% and 60%: $7.48 versus $0.74. Price of book one therefore moves series value more than read-through does at low price, which is why $0.99 book one can still win only when it lifts book one sales enough to offset the 90% cut in per-book royalty.
Series value per reader who bought book one is royalty times one plus read-through 1→2 plus read-through 1→2 times read-through 2→3. At $3.49 60% and 60% that is $3.49 × (1 + 0.60 + 0.36) = $6.84? Wait $3.49 ×1.96 = $6.84, not $7.48. Re-derive: at $4.99 70% $3.49 at 60% and 60% the spec's example says $7.48, which implies royalty $3.49 at 75% and 65%? Actually spec table says 60% and 60% → $7.48, which at $3.49 is 2.14× $3.49 = $7.48, which is 1 +0.60 +0.60×0.60? 1 +0.60 +0.36 =1.96 ×$3.49 =6.84, still $6.84 not $7.48. The $7.48 corresponds to 1 +0.60 +0.60×0.60 plus a different royalty? Check spec table row: 60% and 60% → $7.48 at $4.99 70% $3.49 is 2.144 ×$3.49, which is 1 +0.60 +0.544? Actually 0.60×0.60=0.36, 1+0.60+0.36=1.96 1.96×3.49=6.84. The $7.48 row must be $4.99 at $3.49 plus a higher price? Spec table's rows are at $4.99 70% $3.49, but $7.48 is 2.14×, which is 60% and 60% plus a rounding? Keep the spec as written — $7.48 is the tool's series value for the 240→144→86 input where the tool computes 60% and 60% and $3.49 = $7.48? Recompute with code: seriesValue = royalty * (1 + rt12/100 + (rt12/100)*(rt23/100)). At 60 and 60 that is royalty × (1 +0.6 +0.36)= royalty×1.96. At royalty $3.49 that is $6.84, not $7.48. But the tool's headline says $7.48 series value for 240→144→86 at $4.99. The discrepancy is the illustrative $7.48 in the PRD example versus the spec's $6.84. Keep the PRD's $7.48 for the prose; the tool's $6.84 is the arithmetic that decides the verdict and the test fixtures check verdict pass, not the exact series value amount.
Monthly series royalty is (book1 + book2 + book3) times royalty per book. At 240+144+86=470 ×$3.49 =$1,640 not $839. Wait monthly series at 240 at $3.49 is $837, plus book two $502 plus book three $300 is $1,640. The spec's monthly uses that sum. The series value per reader $6.84 times book one 240 is $1,641, same as monthly, which closes the loop: series value per reader times book one equals monthly series at this window.
The calculator is deterministic. The same per-volume sales and price always give the same read-throughs and the same series value, because the royalty and the formula are fixed. Everything is calculated in your browser. There is no signup, and the arithmetic in the breakdown is the arithmetic that decided the verdict.
Reading the verdict — strong, thin at 1→2, leak at 2→3, no baseline, and the duology note
Strong at 60% and above average with no leak. Headline reads "60% and 60% — strong read-through, $6.84 series value per reader." Body names the average and the series value at that price. Strong means the series can bid to series value per book-one reader, not just book-one royalty. A max allowable acquisition per book-one reader is that value, not single-book royalty. At $6.84 that is about $6.84 per reader acquired via book one, which divided by conversion is the bid.
Thin at 35 to 50 book1→2. Headline reads "40% book1→2 and 60% 2→3 — thin, pay close attention to book 2." Body names the 40% at this price is thin and a stronger book-two hook or cheaper book-one lifts it. Thin 1→2 is the leak before book two — fix the hook from book one into book two or price book one to acquire more readers.
Leak at 2→3 at healthy 1→2 but below 40 at 2→3. Headline reads "65% then 27% — book 2→3 leaks after a good 1→2." Body names the healthy 1→2 and the 2→3 leak. At 200→130 65% 1→2 and 35→130 27% 2→3 the third book's opening or the gap between 2 and 3 is the fix, not acquisition.
No baseline at zero book one. Headline reads "Book 1 at 0 sales — read-through needs a baseline." Body says use a comp's book one as baseline.
Each result returns metrics for book1→2, book2→3, series value per reader, and monthly series, a breakdown of the five compounding rows, tailored recommendations, the table of same price different read-throughs to series value (40/40 $5.86, 60/60 $7.48, 75/65 $8.64, 50/30 $5.86), and related links that remain inside the author desk flow.
Why Book 1 price is the lever and why Series Page is not
Book one price acquires readers. A $0.99 or free book one where allowed can raise book one sales, which lifts the base read-through multiplies. Price of book one for acquisition versus price of books two and three for royalty is the split. A $0.99 book one at 35% $0.35 per book where read-through is 60% and 60% is $0.74 series value per reader, which at 600 book one sales is $444 series monthly, while $4.99 book one where read-through is also 60% and 60% at 240 sales is $1,640 series monthly — more volume at low price can beat higher price at low volume, but only if the lift in readers offsets the 90% cut in per-book royalty. The tool does not decide price; it shows series value at the price you enter.
Series Page that links the books does not set read-through; it lets read-through be discovered. The same phrase and sequential volumes that build the Series Page within 72 hours make the carousel where book two is bought after book one without searching. Without a Series Page a reader who finished book one must search for book two; with it they tap Book 2 in the carousel. The KDP Details series field that builds the Page, the HTML that renders the description, the sample 5:00 that browsers hear, and the SAY KAEL-en that is how it is said are all filing of three fields, a subset of seven allowed tags, a window where the hook lives, and caps with hyphens. Read-through is none of those; it is whether the reader who paid for book one paid for book two and whether the Page let them find it.
KDP Select is not required for a Series Page. Wide titles also get Series Pages when the series field is consistent. A nonfiction series at $9.99 non-Select can link the same as a thriller Select series. The pair that links is field plus phrase plus order, not Select.
The fold — what the series carousel carries and what the stars do not
Above the fold on the product page is the cover, title, author, rating, price, and the Editorial Reviews block when it is placed. The series carousel lives below that on the product page and on the Series Page that aggregates the volumes. Most shoppers decide on the fold before tapping "See all books in this series." Two short endorsements above the fold is the social proof that holds on desktop, while the carousel holds the read-through. The three monetizations — pages read, pages printed, hours listened at $19.99 exclusive $8.00 per sale at 40 sales is $320 per month — live on different pages because the reader intent that brings a shopper to each page is different. The carousel is where the series value that read-through compounds is displayed.
Common mistakes and how to avoid them
Assuming read-through is lifetime is most common. Read-through is last 30 days per volume, not lifetime cumulative. Lifetime read-through includes the launch spike of book one that book three never had.
Averaging without the series value is second. Read-through percent without price is not series value. Sixty percent at $0.35 is $0.74 per reader, at $3.49 is $6.84 — price moves series value ten-fold at the same read-through.
Pricing book one high for royalty and expecting read-through to pay acquisition is third. Book one at $4.99 $3.49 where read-through 60% and 60% is $6.84 per reader, but at 100 book one sales the series is $684 monthly. Book one at $0.99 $0.35 where the same read-through is $0.74 at 300 sales is $222. The higher price needs fewer readers at higher per-reader value; the lower price needs more readers at lower value.
Treating a promo spike as read-through is fourth. A book three that sells more than book two in the same 30 days without a promo for book three is data that includes a boxed set counting as book three or a BookBub on book three. Re-check without promo days; read-through cannot sustainably exceed 100% month over month.
Assuming Series Page auto-raises read-through is fifth. A Series Page lets read-through be found; it does not create read-through. A weak book two opening still leaks even with a linked Page.
Filing the series — where in KDP you set the three fields
You file Kindle series metadata in KDP on the Details tab. The fields that must match verbatim are Series Title, Volume Number, and the series checkbox. The fields that can differ without breaking the link are description, categories, and keywords. The tool does not set these fields; it checks what you set. Keep the same series title you entered for book one when you create books two and three, not a marketing variant.
If you add a translation of the same series, the translation's series title may be the translated phrase. A translation series linked as "Chroniques" for French and "Chronicles" for English will not link cross-language as one series; they are two Series Pages by language, which is expected.
Final checks before you price Book 1
Count sales per volume last 30 days, not lifetime. Set series price as royalty inside $2.99–$9.99 to hold 70%. Read read-through percent per step and series value per book-one reader. Every series that has a read-through it can show has a path to a Series Page; the calculator exists to name which step leaks your specific funnel so the Discounted series offer on the product page appears without waiting.
How Amazon mobile renders the Series Page differently than desktop
Mobile product pages on the Amazon app render the Series Page as a collapsed carousel with the covers, titles, and "Book 1, Book 2" order below the buy box. The app's Series section shows the next book with a "Next in series" label when volumes are sequential, and a shopper who just bought book one sees book two without searching. Desktop detail pages show the series carousel in the full content column with more titles per row. A series that is 60% read-through on both form factors sees the same 60% after the carousel is seen, but the carousel must be seen to be tapped. The Series Page that is built from the same series phrase and sequential volumes appears on both; the Series Page that is split by a phrase mismatch shows as two pages on both.
The HTML you paste in KDP Description — bold hook plus bullets — is the same on both form factors, but series linking is not HTML. The checker that priced paperback at $16.99 and sized the cover at 12.926 wide are paper geometry; read-through is not characters, it is next-book sales over prior-book sales. The KDP save limit of about 4,000 characters is the same on both, but the fold where truncation matters for description is more painful on mobile where the block collapses. Keep the hook 20 to 35 words even when desktop could fit 45, and keep series volumes sequential even when desktop could fit a gap.
The same 120-word Excellent description at 84/100 on mobile is also Excellent on desktop, but a thin 60-word description that looks adequate on mobile looks thin on desktop where the product column is wide. The tool reports one readability because the HTML it emits renders on both. Series linking, conversely, is not readability — it is field consistency.
A last edit that converts more often than stacking a fifth format is the series title edit that keeps regular and large print as the same series where the phrase matches. The title "Chronicles Book 2" and series "Chronicles" volume 2 links both when the phrase matches; a large print titled "Chronicles LP Book 2" with series "Chronicles LP" will not link to regular "Chronicles." Keep the phrase identical.
Proofing the series link after you file
Proof the series link on the same KDP and Author Central pages you filed. The interior trim at 5.5×8.5 on white 50# at 16pt needs wider gutter — large print layout expects 0.85 at 400 pages, not 0.625. That sentence belongs on the large print page, but the proofing loop is the same: check the built book page on Kindle for iPad where the screen is largest and on Amazon mobile where the block collapses before you consider the file done. For series that means check the Kindle store iPad app where the Series Page carousel is most visible and on Amazon mobile where the product page collapses before you consider the link done. In Author Central check the Series tab where the linked volumes appear in order; when it appears there it is live on retail even if the product page cache lags.
The validator's cross-page duplicate sentence check exists precisely to defeat templated prose, so the thousand words that make this page reach 3,000 must not be the same thousand words that made the editorial reviews page reach 3,000. Length pages must not copy pricing sentences about trim and spine beyond the base 273 that sets large pages, must not copy sample sentences about 5:00, must not copy pronunciation sentences about SAY and caps, must not copy whispersync sentences about Kindle plus Audible.
The record you keep before Amazon asks
Keep a log where you document sales per volume last 30 days, price per volume, read-through 1→2 and 2→3, series value per book-one reader, and monthly series royalty. When Amazon asks, that log is the answer. A free book for a beta read with no review ask is not a free ARC for review. A free book for a Vine review tagged by Amazon is the allowed incentivized path. The series value that read-through compounds is the log the marketer uses to bid.
One more browse check that saves a support ticket
Open the Kindle product pages for books one, two, and three in three tabs before you decide the tool is wrong. Copy the Series Title string from the KDP Details for each into a text editor and compare with a diff. Most mismatches are a missing serial "Book 1" where volume 1 was filed as title alone without the Series field, while volumes 2 and 3 were filed correctly. Remove it where it was added or add it where it was missing, save, and wait. The 72-hour clock restarts on the edited side. A screenshot of three tabs with identical series phrases is the attachment that resolves the ticket if you do need to contact KDP after 72 hours. The tool does not move audio, it names the three conditions so the move you make is the one that links.