BardMetrics Amazon sales rank
Amazon sales rankings
Amazon provides data about book sales via their interface (available in the "book facts" section of a book's Amazon page). This data can be a bit difficult to understand since Amazon purposefully guards the algorithm utilized to generate it. The proprietary formula used to compile the Amazon Sales Ranking of a given book is a large secret of the Amazon company but bloggers, authors, and general internet denizens have spent some time analyzing what the numbers actually mean.
The Amazon algorithm
The Amazon sales ranking of a given book is calculated the moment a book is sold. If you happen upon a book without an Amazon sales ranking, that means the book has not yet sold a single copy. As of 2004, the Amazon Sales Ranking Data does include sales made both on the Amazon Marketplace and in e-book editions.
The Sales Ranking of a book is (purportedly) recalculated every time that book makes a sale. The lower the number of a book's sales ranking, the higher number of books actually sold (so a #1 book has sold the most copies out of all books available on Amazon during a given time period). At the moment of a sale, a book's ranking will drop. The longer a book goes without a sale, the more likely it is that another book has sold thus bumping book A from its higher ranking spot. This results in peaks and valleys in book-tracking over the course of a given time. If the book in question sells a great many copies, these peaks and valleys will be closer together in a real-time analysis, thus allowing you to take a better average in a shorter period of time. If the book is a slow-seller, it will take longer to obtain a true average since the peaks and valleys are further spaced out.
What does a rank mean?
According to author Theresa Regan's 2013 survey of the Amazon Ranking System, you can make a rough estimate of the number of books sold on a per-day basis via that book's Amazon rank in accordance with the following list:
|Amazon Ranking System|
|Amazon Best Seller Rank||Number of books sold per day|
|50,000 to 100,000||1|
|10,000 to 50,000||5 - 15|
|5,500 to 10,000||15 - 25|
|3,000 to 5,500||25 - 70|
|1,500 to 3,000||70 - 100|
|750 to 1,500||100 - 120|
|500 to 750||120 - 175|
|350 to 500||175 - 250|
|200 to 350||250 - 500|
|35 to 200||500 - 2,000|
|20 to 35||2,000 - 3,000|
|5 to 20||3,000 - 4,000|
|1 to 5||4,000+|
One rule of thumb which has been proposed by Morris Leventhal of FonerBooks is to check back on a book's rank twice a week over a period of four weeks. Add the ranking numbers you compile then divide by eight to find an average Amazon Sales Rank for that period.
How much does a rank change?
Again, this will depend upon the frequency of a sale. A top 5,000 book will generally only fluctuate by no more than 20%. Titles between 10,000 and 20,000 can change as much as 60%, and titles ranked under 50,000 will make wild swings.
Further reading and sources
Dog Ear Publishing "What's Your Rank... on Amazon?"
Leventhal, Morris. "Amazon Sales Ranking and Author Rank"
Regan, Theresa "Sales Ranking Chart"
Sullivan, Robin. "Demystifying the Amazon Sales Rank."