My ad was accepted by BookBub! – Should I be excited?

Actually, no. My ad was not accepted by BookBub. The following helps explain why. is reputed to be one of the best sites for advertising a ebooks. Because of this reputation they are flooded with requests to place ads. Some authors become quite excited when, after applying for months, BookBub finally accepts their ad. For some, the ad does indeed result in a gratifying volume of downloads or sales.

BookBub vets ads carefully and charges prices commensurate with performance. As of July 2014, ad prices, which depend on genre and book price, range from $40/day (a free LGBT book) to $1,600/day (a $2+ mystery novel). They are up front about the results an advertiser might expect, both in downloads (for free books) and purchases, based on genre.

The fact that BookBub knows roughly how much money a book ad will generate for the advertiser explains why ad prices depend both on genre and book price. One may calculate the anticipated royalties from sales using Amazon KDP as a guide. Here I assume the following book prices: <$1 = $0.99, $1-$2 = $2, and $2+ = $3. The following table gives the royalty return on investment (ROI) using ROI  = (royalties – ad price)/(ad-price):

bb ROI per price sheet

For free books, the ROI could be measured in term of downloads per advertising dollar. The average across genres turn out to be about 100/$ or one cent per download.

Some genres and book prices do not seem promising in this simple analysis. It is unlikely, however, that each price point will have the exact number of sales listed. It may well be that a $2.99 book has a substantially lower sales volume than that listed, and that a $0.99 book, higher. That will be addressed in a future post.

The prices within a genre are a simple progression: an ad for a book priced $0.01 to $.99 costs twice as much as an ad for a free book in the same genre, an ad for a $1-$2 book costs three times free, and an ad for a $2+ book costs five times free.

Using I obtained their price list from February of 2014. There has been an average 1/4 increase in ad prices, a 2/3 increase in estimated downloads and sales, and a doubling of the number of subscribers. This is dramatic growth indeed.

I was curious both about the kinds of books they accept and how those books fare on Amazon during the day of the ad. I happened to have the tools at hand (described elsewhere on this site) to feed that curiosity. To that end I noted the 15 books featured on the first page of BookBub’s Latest Deals list and then pulled down each book’s Amazon page. This gives a picture of the types of books featured. By doing this hourly, I was also able to assemble a picture of how each book’s Amazon rank changed on the day of the ad. That will be in a future post.

The below information is based on twenty days of data, comprising 300 books, about a third of which were free.

The ads by genre:

Here we see breakdowns by the categories BookBub uses and by more broad categories. (Some romances are teen and young adult and here they are kept in the T&YA broad category. I put romantic suspense and paranormal romance into the romance broad category.)

by bb genre

BookBub categories.

by broad genre

Broad categories

This in part helps explain why my ad for my science fiction novel was not accepted. Given that SF has one of the higher anticipated ROIs (fantasy is even higher), and generates more traffic than teen and young adult, it is puzzling why BookBub eschews fantasy and SF. One reason may be the demographics BookBub is seeking. With perhaps 50,000 click-throughs a day to Amazon, BookBub’s affiliate revenue* may be substantial. If each click-through generate a dime on average, that would exceed their revenue from the sale of book ads.

If they can trace that revenue to the fans of particular genres, they may have an incentive to promote genres read by shoppers. I wouldn’t be surprised if the typical romance reader was more of a shopper than the typical science fiction reader. Just saying.


The ads by Amazon rating and number of reviews:

BookBub is notorious for vetting books by their Amazon ratings and number of reviews. At one time the rule was 4.0 or greater rating with ten or more reviews. The criteria sound more subjective now.

I was surprised to see a few books with ratings below 4.0 among the ads. The median rating (half of books fall below the median, and half above) was 4.4 for both free and paid books, with one at 3.2(!). It’s possible that the lower rated books saw their rating fall between the time the ad was accepted and it ran.

amazon rating

amazon reviews

I was also surprised to see one book with no Amazon reviews whatsoever, although not an indie. While 7% of books had less than ten reviews, the median was a hefty 90 reviews.

The ads by publisher:

I recently read that BookBub is no longer for indie books. That’s not entirely true.

Here “Unknown” refers to publishers who represent only one or two authors in the 60,000 books I looked at previously. One or both of these authors may be pen names, so most of the publishers labeled “Unknown” are likely indie published.

discounted by publisher

free by publisher

It’s apparent that BookBub does still cater to indie books, particularly the free ones. Below is a table of the average rating and number of reviews for books by each publisher category, FWIW.

by publisher


The ads by discount:

To be one of the “Latest Deals” a book must be free or discounted. The median discounted price is 25% of the original price. There is a peak around 33% because this typically represents a $2.99 book (Amazon’s minimum price to earn a 70% royalty) discounted to $0.99 (the lowest price Amazon allows the publisher to set).

discounted price as percent

No book in my sample was discounted less than 50%. Most books are at the $0.99 price point.

discounted price



Placement on the Latest Deals list:

It is also worth noting how ad placement on the first page of the list varies with genre and price. The first chart (and this may be a bit confusing) is a bubble diagram that plots average placement (higher on the chart means closer to the top of the list) by genre versus number of ads during the 20 days, with the more numerous ads toward the right (this is also indicated by bubble size). The single Teen and Young Adult ad appeared in the first position, as did all five Literary Fiction ads. Note the cluster in the top right corner where a large volume of Mysteries, Thrillers, and Contemporary Romance novels have enjoyed prominent placement. For example, Mysteries comprised 39 ads with an average placement position of 2.5.

placement by genre and volume

The second chart of average original/discounted price shows that the first slot on the list tended to favor the more pricy books. (More in a future post on the sales implication of being first or second on the list.) The first slot was typically populated by discounted books (only one free book made it into the first slot) and the second position was usually a free book.

price and placement

 Starting rank (book rank when the Latest Deals page first goes up) also correlated with placement.

starting rankIn my sample there was no apparent correlation between the type of publisher and placement in the critical first two slots.

I hope this information is helpful. This data certainly helped me understand why my ad was rejected.

Again, if you have suggestions for new ways to look at the data, please post these in the comments. See my next post for an analysis of the actual performance of BookBub ads.

*Amazon can pay the referring website up to 8.5% of everything the customer buys if the website has been accepted as an Amazon affiliate.


Filed under Indie Publishing Business