KDP series read-through calculator: what one new reader earns you

What to enter

Add one row for each book in the series, in reading order.

• Price: the Kindle price on Amazon.com. Enter 0 for a free book. If a price is below the lowest KDP allows for your file size, the calculator uses that lowest price instead.
• Copies sold: use the same dates for every book. KDP Reports lists orders for each title. Readers take a few weeks to finish one book and buy the next, so a longer window, such as the last 90 days, gives a steadier number than a launch week.

Planning a book that isn't out yet? Enter the copies you expect. Book 1 at 100 and book 2 at 55 models 55% of readers moving on.

Everything under File size, KU reads, ads, and deals is optional. Leave it closed and you get the answer from sales alone.

• Converted file size: KDP charges a delivery fee on 70% sales, based on the size of your converted file. Your book's pricing page in KDP shows it. Empty uses 2 MB.
• Kindle Unlimited (KU): for books in KDP Select, the program that puts your ebook in KU. Enter each book's KU pages read over the same dates as its sales. Then add its KENPC, which is KDP's page count for KU, shown on the book's Promote and Advertise page in your Bookshelf. Last, add the KENP rate, which is what KDP paid per page that month, and the month it's from. The calculator never guesses a rate, so once you enter pages, the rate and month are required.
• Ads: what your ads cost now, the share of ad clicks that turn into book 1 orders, and a profit you want to keep from each reader. Enter the cost as ACoS, which is Amazon's ad spend ÷ ad sales, or as a dollar cost per new reader. Use cost per reader for Facebook or BookBub ads, since only Amazon reports ACoS.
• Book 1 deal: a sale price for book 1, or 0 for free, and whether it's a Countdown Deal or an ordinary price change. The last field is your guess at the share of deal readers who go on to buy or borrow book 2.

The deal read-through doesn't show up again in the result. It changes two numbers: what each deal reader is worth, and how many deal copies match one full-price reader. Leave it empty and the calculator uses your own book 1 to book 2 rate. Try a few values, since people who got book 1 free may be less likely to carry on.

How to read the result

How do you calculate series read-through?

Divide each book's readers by the readers of the book before it. If book 1 sold 100 copies and book 2 sold 55, read-through from book 1 to book 2 is 55 ÷ 100 = 55%. Always put the later book on top. Swap them and you get 182%, which means something else entirely.

Each step gets its own rate, worked out from your own numbers. Later steps are often quite different from the first one, so the calculator never copies one step's rate to another.

Kindle Unlimited reports pages read, not readers. So the calculator turns pages into full reads: pages read ÷ the book's KENPC. That's an estimate, not a head count. Ten people who each read half the book look the same as five who finished it.

Why is my read-through above 100%?

Because a book had more readers than the one before it over your dates. That's real, not an error. The usual causes:

• A launch or a promo on the later book, or on book 1 a month earlier, so the two books' sales don't line up in time.
• Kindle Unlimited. A book can get more KU reads than the book before it, especially a short one. KU full reads count as readers.
• Ads or newsletters for a later book, which bring readers who skipped the earlier one or bought it some other time.
• Short dates. In a 30-day window, the readers buying book 3 may have bought book 2 the month before.

A longer window, such as 90 days, smooths most of these out. A step above 100% still adds to the reader's value in the calculator, so check whether it reflects what you expect to keep happening.

What is one new reader worth?

Add up everything the series earned over your dates, then divide by the number of book 1 readers. That's the value of an average new book 1 reader across the series.

This treats every later-book reader as someone who came in through book 1. If you advertise book 2 or 3 directly, the per-book table's Worth from this book on column shows what a reader who starts there brings in.

The royalty uses KDP's Amazon.com rules. The 70% rate applies from $2.99 to $12.99 since July 7, 2026, and the delivery fee is $0.15 per MB of your converted file. See KDP's eBook list price requirements and digital book pricing. For the royalty on one book, use the KDP royalty calculator.

How much can I spend on ads to get one new reader?

Up to what a reader is worth, if you're happy to break even. In the example above that's $6.53 a reader. Set a profit to keep per reader, and the most to pay drops by that amount.

Amazon Ads reports ACoS: ad spend ÷ the sales the ads brought in. One ad sale of book 1 brings in book 1's price. So the break-even ACoS is the reader's value ÷ book 1's price.

Amazon decides which sales count as coming from an ad. Treat your ACoS as Amazon's view of your ads, not an exact count of new readers. Ad sales also leave out Kindle Unlimited pages read, which Amazon Ads reports apart. If many of your new readers borrow book 1 in KU, your reported ACoS can run higher than this break-even and still pay off.

To turn that ceiling into a bid, add your conversion rate: book 1 orders ÷ ad clicks. At 10%, the highest cost per click for the example series is $0.65. The KDP book ads bid check does the same for one book, with no read-through.

How does Kindle Unlimited change the number?

A KU reader pays you per page, not per sale. For a 300-page book at $0.0045 a page, a full read pays $1.35, while a $4.99 sale pays $3.28. So adding KU readers can lower the value per reader, even though your total earnings go up.

KDP pays for each page a reader reads for the first time, up to 3,000 pages per book per borrow. A book with a KENPC above 3,000 pays as if it had 3,000, and the table marks it Capped. See KDP's KU royalties and KENPC help.

The KENP rate changes every month, and KDP finalizes it near the 15th of the next month. KDP doesn't publish a per-page rate in its help pages, so the calculator has no default. Use the rate for the month your pages were read, and enter that month too. To estimate one book's KU earnings, use the Kindle Unlimited KENP earnings calculator.

Should I make book 1 free or put it on sale?

It depends on how many deal readers go on to book 2, and only you can guess that. The calculator works out what one deal reader is worth. That's the royalty on book 1 at the deal price, plus the share who read on × what a book 2 reader is worth.

It also shows how many deal copies it takes to match one full-price reader. If that number is 2, a free book 1 needs to reach at least twice as many readers as the paid one to come out even.

At $0.99, a Countdown Deal pays more than a plain price change. A Countdown Deal is KDP's timed discount for books in KDP Select, and during it you keep the royalty rate the book earns at full price. So a $4.99 book stays on 70%. Change the price to $0.99 yourself and it drops to 35%. See KDP's digital book pricing.

KDP's rules for each kind of deal:

The calculator checks Countdown's price rules. It doesn't check KDP Select enrollment or the 30-day and 14-day price windows.

What is a good read-through rate?

There's no reliable benchmark. Many author guides say "around 50 to 60%" from book 1 to book 2, including Kindlepreneur, but none of them share a sample or a method. Genre, price, and KU share all move the number. So the calculator doesn't grade your rate.

Compare your rate with your own past months instead, and use the 10 more points to book 2 adds line in the result to see what improving book 1's ending or back matter is worth to you.

Why might KDP pay me less than this?

• Delivery fee. It depends on your converted file, not your upload. Check the size on your pricing page.
• Other stores. The calculator uses Amazon.com rules and US dollars. Other stores have their own VAT, delivery fees, and KENP rates.
• Price matching. If Amazon matches a lower price elsewhere, you earn on that price.
• KU rate. The month's rate can change until it's finalized near the 15th of the next month.
• Refunds and returns, which the calculator doesn't model.

What doesn't this calculator cover?

It covers Kindle eBooks on Amazon.com. It doesn't cover:

• Paperbacks and hardcovers. Each needs its own page count and printing cost. Use the KDP royalty calculator per book.
• Audiobooks and box sets, which sell as separate products.
• Other Amazon stores and currencies.
• Whether your book is in KDP Select or eligible for a deal.

It runs in your browser and never touches your KDP account.