If your book is in Kindle Unlimited, some of the readers your ads find never buy it. They borrow it and read it, and you are paid per page. ACOS ignores every one of those pages. For a book with plenty of page reads, that can make profitable ads look like a loss.
What KENP is
KENP stands for Kindle Edition Normalized Pages. It is how Amazon counts pages read by Kindle Unlimited readers, using a standard page count (KENPC) so that font size and device do not change the number.
- Pages are counted from the book’s start-reading location onwards.
- A single customer can earn you at most 3,000 pages per title.
- You are paid a share of the monthly KDP Select Global Fund — $69.4 million for August 2026 — in proportion to your share of all pages read.
- The per-page rate is announced around the 15th of the following month, so your KENP earnings are an estimate until then.
Why ACOS cannot see it
ad spend ÷ ad sales × 100
Ad sales are the value of books bought. A borrow is not a purchase, so its page reads never reach this number.
The Amazon Ads console does show KENP pages read and estimated KENP royalties for your campaigns, as separate columns. They only cover reads attributed to an ad, and they never feed into ACOS. So a campaign can show an ACOS far above your break-even while the page reads it bought quietly pay for it.
A worked example
One month, a $4.99 eBook in Kindle Unlimited earning about $3.40 per sale:
| Figure | How | |
|---|---|---|
| Ad spend | $100.00 | |
| Ad sales | $119.76 | 24 sales × $4.99 |
| ACOS | 84% | 100 ÷ 119.76 — above the ~68% break-even |
| Royalties from those sales | $81.60 | 24 × $3.40 |
| KENP pages read from ads | 20,000 | |
| KENP royalties | $80.00 | 20,000 × $0.004, an illustrative rate |
| Profit from the ads | +$61.60 | 81.60 + 80.00 − 100 |
On ACOS alone, this campaign loses money and you would cut it. Counting the page reads, it made $61.60. The rate used here is only an example. Take your real per-page rate from your KDP reports, because it changes every month.
sale royalties + KENP royalties − ad spend
What to do about it
- Add the KENP columns to your campaign view in the Amazon Ads console, so page reads sit next to spend.
- Judge Kindle Unlimited books on profit, not ACOS: sale royalties plus KENP royalties, minus spend.
- Look at KENP over at least a month. Borrowed books are read over days or weeks, and the per-page rate is only final mid-month.
- Remember read-through. A reader who finishes book one and borrows book two weeks later is worth more than either ad shows, and the attribution window will not credit it.
Series and read-through
Amazon credits a sale or a page read to an ad only within 14 days of the click. A series reader who moves on to books two, three and four over the following months creates real income that no ad report attributes to the ad that found them. For the first book in a series, a higher ACOS can be the right target, as long as you have measured read-through rather than hoped for it.
GuideACOS vs ROAS vs TACOS: What Each One MeasuresTACOS shows whether ads are growing the whole book, borrows and all.Common questions
What is KENP on Amazon KDP?
KENP means Kindle Edition Normalized Pages: the standard page count Amazon uses to measure how much of your book Kindle Unlimited readers read. You are paid per KENP page from the monthly KDP Select Global Fund.
How much does KDP pay per KENP page?
The rate changes every month and is announced around the 15th of the following month. It is a fraction of a cent per page. Your KDP reports show the exact rate for each month.
Does ACOS include Kindle Unlimited page reads?
No. ACOS divides ad spend by ad sales, and a Kindle Unlimited borrow is not a sale. The Amazon Ads console shows KENP pages read and estimated KENP royalties separately.
Can I see KENP in Amazon Ads?
Yes. The console reports KENP pages read and estimated KENP royalties for your campaigns, but only for reads attributed to an ad, and not as part of ACOS.
Is Kindle Unlimited worth it for books I advertise?
It can be, because every reader your ad brings in can pay you by borrowing as well as buying. Whether it is worth it for a particular book is a profit question: compare sale royalties plus page-read royalties against spend.
- KENP = Kindle Edition Normalized Pages: Kindle Unlimited reads, paid from the monthly KDP Select Global Fund.
- ACOS ignores page reads, so a Kindle Unlimited book can look unprofitable on ACOS and still make money.
- Judge Kindle Unlimited books on sale royalties + KENP royalties − ad spend.
- The per-page rate is final only around the 15th of the next month; take it from your KDP reports.
- Read-through beyond the 14-day attribution window is real income that no ad report credits.