The Author Helper Suite Help – Sell-Thru/Read-Thru

Knowing how each our different series are doing as a whole helps us make the best decisions for our business.

But what factors should we be looking at, and how do we use those to make the right choices?

While there are many, one of the most important is knowing your sell-thru and read-thru for your series.

Sell-thru is the percentage of buyers who buy each subsequent book in a series. Unless your series has multiple entry points or doesn’t need to be read in order, you’ll likely see book one having the most sales with a decrease each book thereafter.

Read-thru is the percentage of Kindle Unlimited readers who go on to read the next book in your series. Similar to sell-thru, this lets you track not only an estimated future revenue—which we’ll go into later—but also diagnose problems your series may be having.

If you’re not getting solid sell-thru or read-thru, you can dig in and try to see what’s happening. 

Maybe the book doesn’t start off with enough of a bang?

Maybe the ending is flat?

Maybe your advertising hit the wrong target audience? 

There are many reasons the numbers aren’t the way you want them, but the first step is simply knowing what those numbers are! 

One of the key components in judging sell-thru/read-thru is timeframe. If you’re looking at too small of a window (1 or 2 days, for example), you may find the data isn’t very useful. We find that 30 days seems to be a decent number.

Factors such as promotions, new releases, and other things can skew the data quite extensively.

How do we factor for this?

Extend your timeframe.

Looking at lifetime sell-thru and read-thru can be quite eye opening, too.

NOTE: You will need to enter the KDP/Amazon Sales Price, Delivery Rate, and KENPC value for each book in the series or the data will be erroneous.

NOTE: This tool only covers KDP/Amazon eBooks Sales and Page Reads.

You do not have to be in Kindle Unlimited to use this tool, but it will only show sell-thru if you’re not.

Sell-Thru Book-to-Book

After you have entered all the necessary data for each book in your series, and you have added enough KDP historical data to fit the timeframe you’re looking to study, you’ll be able to get feedback on your data.

There are two separate sell-thru numbers. One is book to book. This is how many buyers bought the next book in the series.

A low sell-thru on this number can indicate a problem with the previous book. Or not. Other factors can contribute but knowing there is a problem is the only way to fix it.

To determine book to book sell-thru, we divide the number of sales of book two by the number of sales of book one. In the example, this is 25 sales divided by 28 sales for a rate of 89.29%.

For book two to book one, we divide book three’s 24 sales by book two’s 25 sales for a rate of 96%.

Sell-Thru Cumulative

The other percentage next to it is the cumulative sell-thru rate. The difference between book to book and cumulative is what we are comparing.

A cumulative sell-thru compares the number of sales of a particular book from the sales of book 1.

Why is this important? It gives you an idea of how much future revenue you can estimate from each sale recorded on The Author Helper Suite.

We’ll talk about this more later.

To determine cumulative sell-thru, we divide the number of sales of book 2 by the number of sales of book 1. In the example (see next image), this is 25 sales divided by 28 sales for a rate of 89.29%.

Notice this is the same sell-thru rate as book to book.

For book 3 to book 1, we divide book three’s 24 sales by book one’s 28 sales for a rate of 85.71%.

Since book 3 is the—current—last book in the series, the series sell-thru as a whole is 85.71%.

This means for every buyer of book 1, about 86% finish the series.

That’s so cool!

Sell-Thru: The Numbers

What’s a good book to book sell-thru rate? That depends. Price can have a major factor in this, as can short term promos and time between releases. This is especially telling with the lifetime sell-thru.

Your goals will determine what rate to aim for. Increasing your sell-thru rate is always a good thing to aim for. 

The more people who finish your series, the more money in your pocket.

Some (very general) suggestions.



$0.99 first in series with subsequent books at full price: 40% or higher—keep in mind the higher the price of book 2, the more likelihood of a lower sell-thru rate. This isn’t always the case. $0.99 first in series with book two—or more—also at $0.99: 50% or higher.

People do hoard $0.99 books often, so a lower sell-thru isn’t unlikely compared to a full price book one.

Full price book one: 60% or higher.

Book one to two tends to be where you lose the most buyers. It could be because the wrong audience is picking up the book. It could be an issue with book 1—like the story or poor back-matter or time between release of book one to two.

Book-to-book after book two: 80% or higher.

Once someone has read two to three of your series’ books, sell-thru should be much higher book to book.

What about cumulative sell-thru? Since this depends on the book-to-book sell-thru, our goal can simply be as high as possible—no suggested rate though.

Read-Thru 

If you’re on Kindle Unlimited, and you have entered the KENPC rate and have sufficient data for your selected timeframe, you will be able to see your Read-Thru data as well. 

Unlike with sell-thru, we don’t divide page reads of one book to another because KENPC differs between books.

First, we have to determine the number of full reads each book had for that time period. To do this, we divide total number of page reads for the book by the KENPC of the book.

In the example (see image below), total full reads of Bangkok Warlock—book one—is 109.43.
Does this mean that 109.43 people completely read the book?

No, it doesn’t. Not everyone who starts a book will finish it. There is no way to calculate that with the information Amazon provides. This is the best we can do.

Just keep in mind that this can affect the read-thru rate, especially with book one to book two.

Partial reads lower total page reads on a reader by reader basis. Because of this, read-thru rate tends to be inflated—as in higher—than it actually is. This is most prominent on book one.

A lower than normal read-thru rate can indicate a bigger problem than initially realized.

Once you have your “full read” amount, you go through the same process as you do for sell-thru, both book-to-book and cumulative.

See image for example.

Read-Thru: The Numbers 

Since the read-thru rate tends to be inflated, the suggested read-thru rates to aim for are higher than the suggested sell-thru rates.

Unlike sell-thru, price has less of a factor with read-thru.

Book one to two: 60% or higher
Subsequent books: 80% or higher

Keep in mind the fewer sales and full reads you have for the entire time period can change the percentage rate quite highly.

The sell-thru rate of 24 sales of book two with book one being 28 sales is 85.71%.

Change the 24 to 23 and the sell-thru rate drops to 82.14%.

Compare that to 100 sales of book two versus 104 sales of book one—a 96% sell-thru rate—and changing book two’s sales to 99—a 95.19% sell-thru rate.

Estimated Future Revenue Sales

Under the last book in the series, you’ll see an estimated revenue amount based on future revenue per reported sale on ReaderLinks.

What is estimated revenue? And how do we use this number to maximize our selling power?

The estimated revenue number considers both your series sell-thru and read-thru as well as the percentage of full reads you receive to sales of book one. We use the cumulative data, not the book-to-book data, to calculate this.

An example:

In this case, Bangkok Warlock has a book one to two sell-thru rate of 89.29% and a read-thru rate of 83.48%. 

If someone buys book one, the royalties received are the price of book one multiplied by your royalty rate minus the delivery fee, in this case $4.99 by 70% minus the delivery fee.

However, only 89.29% of those buyers move on to book two. How do we account for them but not for the 10.71% who do not buy book two?

First, we determine the royalties received for book two. This is the same formula as book one. 

Then we multiple the royalties received by the cumulative sell-thru rate of book one to two.

We do the same process for book three. Find the royalties received and multiple by the cumulative sell-thru of book three to book one.

Once you’ve done that for all the subsequent books in the series, you add those numbers together to get your estimated revenue per reported sale.

Estimated Future Revenue Reads

But wait. What about page reads?

For a lot of authors in Select—the program that gets you into Kindle Unlimited—a large percentage of revenue comes from page reads, not just sales.

 To determine your estimated future revenue per “full” read, do the same process as you would for sales.

 Instead of royalty rates, we want to know the revenue earned if someone fully reads our book.

We get this by multiplying the KENPC for the book by the page read rate.

But the page read rate changes monthly and we don’t know it until the month has already passed.

 It’s suggested using either a six month average or just use a low rate. The Author Helper Suite is using $0.004.

Once you have the revenue from one full read, you do the same process as the sell-thru estimated revenue by multiplying each book’s revenue for one full read by the cumulative read-thru rate.

Add those numbers together to get the estimated revenue from page reads.

Estimated Future Revenue Tool

The estimated future revenue per reported sale through The Author Helper Suite includes both the sales and page read revenues.

We could simply add them together, but this ignores the percentage of reads you receive versus sales. Unless you get a 1-for-1 reads-to-sales, adding the two numbers together will give an incorrect estimate.

To determine reads-to-sales, divide total full reads of book one by total sales of book one.

In this example, there are 109.43 reads versus 28 sales for a reads to sales percentage of 390%. In other words, for every sale reported on ReaderLinks, you’ll likely get 3.9 full reads.

That’s a lot compared to a 1-read-to-1-sale ratio.

Now, take the page read revenue and multiple it by the reads-to-sales ratio—390% in the example.

This gives you a better estimate of actual future revenue.

However, nothing is guaranteed, and if you’re making important decisions—like if you are making a profit or loss on your ads—adding together the estimated revenue of page reads and the estimated revenue from sales assumes your ratios and numbers remain the same.

That’s a dangerous assumption to make.

To create a more conservative—and safer—estimate, divide the page read revenue in half before adding the sales revenue.

This number is your estimated future revenue per reported sale.

Finding this number takes time and effort, especially if you haven’t done it much before.

Fortunately, The Author Helper Suite now generates this number for you. No extra work on your part!

Amazon ACoS (Advertising Cost of Sales) 

This value will give you an estimated profitable value you can use to know what your safe ACoS percentage is for Amazon, based on the timeframe you selected for data analysis. 

Taking the estimated future revenue per reported sale on ReaderLinks and dividing it by the full sale price of book one will give you the ACoS on the Amazon ads dashboard to keep under to remain profitable.

This lets you know at a quick glance whether an individual ad or your ads for a specific book as a whole are making money or losing it.

Profitable Bid Calculator 

The profitable bid calculator makes it easy to figure out your conservative max bid and conservative minimum conversions based on either your conversion rate or acpc respectively.

How do we use this?

To calculate a profitable bid, divide the estimated future revenue per reported sale on The Author Helper Suite by the estimated average conversion rate of your ads.

This is for sales only and doesn’t consider conversions based on page reads. The calculation for estimated future revenue already takes those in to consideration.

In the example, if the conversion rate is 20, our profitable bid is $0.88.

You can use this as either your starting bid with Amazon ads or work up to it over time.

You can change your estimated conversion rate to find the applicable bid for you. Keep in mind conversion rates can and will change over time and per ad. Better to estimate a lower conversion than a higher one.

A good starting place is 30 to 50 if your book is in Kindle Unlimited. And 15 to 20 if it isn’t—or the price of the book is $0.99.

Profitable Conversion Calculator

The profitable bid calculator makes it easy to figure out your conservative max bid and conservative minimum conversions based on either your conversion rate or acpc respectively.

Want to evaluate specific ads that are already running?

You can find your profitable sales conversion by working in the opposite direction.

Divide the estimated future revenue by the current aCPC of the ad or ads of the book.

This will give you the minimum sales conversion rate to remain profitable. (Sales conversion rate is based on the amount of clicks on ad(s) per reported sale.

In the example, an aCPC of $0.25 allows up to 70 clicks per sale to stay profitable.

You can adjust the aCPC on the provided calculator.

Special Thanks!

Felicia Beasley from Procyon Enterprises, LLC (home of Level Up Author Marketing) was instrumental in helping us to build this tool and for writing this help file!

Mal Cooper, author of the Help! I’m an Author series provided the spreadsheet she created to help us get started.