Demystifying the Amazon Sales Rank

I’ve been asked this many times, most notably today on a Shelfari Writer’s Group. How can I tell how many books I’ve sold on Amazon from my sales rank? The answer is simple – you can’t. The formula is a proprietary and a highly guarded secret of Amazon. There are many minds larger than mine who have spent months and sometimes years studying this subject and they can’t tell you either. But that doesn’t mean you can’t find out some good information from your sales rank.

WHAT IS THE AMAZON SALES RANK
The picture to the left was taken from my husband’s book “The Crown Conspiracy”. The arrow indicates the current sales rank is 57,194 which means quite simply that at this point in time there are 57,193 books that are “better” selling then his at this point in time. Sounds pretty bad huh? Not really when you consider the number of books on Amazon (The worst rank I have seen is 6,958,847 (and I’m sure there are larger ones) which means his book sells better than at least 6,901,653. Not too bad in that context. The number really has the most to do with how long it has been since your last sale.

I DON'T SEE A RANK WHAT DOES THIS MEAN
It means that you have not sold a single book through Amazon yet. As soon as you buy one book you'll get a rank.

VOLATILITY
Now keep in mind that the rank is “at that point in time” and the numbers are updated regularly (I did some experimentation and it seems to change once an hour). The best rank I’ve ever seen for him is 27,873 the worst is 527,890. The number can vary wildly even over the period of a single day for instance on Feb 8th the ranking varied from 70,891 - 321,204).

SEASONALITY
Remember to take seasons into account when assessing your sales rank. Students buying for the upcoming semester can clog the top spots with textbooks and paperback classics in the late summer and midwinter seasons. Likewise, books without gift appeal will probably see a significant drop in the holiday months.

HOW IT WORKS?
As mentioned earlier, as soon as a single book is sold you get a ranking. Then the clock starts ticking. For each hour that goes by without a sale you climb a bit higher in the ranking (remember low rank = good, high rank = bad - you would rather be ranked 100 then 10,000). This change in ranking indicates that while you had no sales other people that were higher than you sold and they filled in the spots pushing you further up in the ranking. Then comes the time when you make a sale. When this happens there will be a dramatic change in the ranking. How far you fall depends on your past sales history and "rate" of sales. (How often you sell). Then the process begins again. This forms a series of peaks and valleys and it is the numbers on these extremes that really give you an idea of your sales. Any number "inbetween" is really just an indicator that it has been awhile since your last sale.

DID I MAKE A SALE?
As mentioned earlier, when your rank falls dramatically a sale has been made. What is more difficult to determine is was that a single sale or multiple copies. Presumably if you sold multiple books you would fall lower than if you sold one but there are two many factors related to other books to look at a single drop and say - oh that was a 1 book drop and this was a two book drop. Just because you "fall far" does not mean that a bunch of books were sold.

So, by tracking your ranking often one thing you can do is see when a sales is made.

ONE OTHER INDICATOR
When your book is first published Amazon will, as a general rule, order 2 copies. When you look at your page it will show “In Stock” and below in red there will be a message” Only 2 left in stock--order soon (more on the way). If you watch your Amazon page frequently, as I do, every once in awhile you will see that message come back then go away which means Amazon just went to the distributor to buy more books. If that message comes back and does not go away…then your book is not selling well. Many “older” titles will have both this message and a high sales rank (say 1,000,000 or more) these books are probably selling only a few a year and Amazon will only be buying them in 1’s and 2’s as they sell.

TRACKING HISTORY
While doing my research I ran across a fantastic site - Titlez (it is free) it shows the sales history for your book over time. From this I was able to determine for instance that I sold at least one book today (1/13/2009) and prior to that I sold at least one on (1/08/2009). I also can see there was a large period of time: 10/29/2008 - 11/20/2008 when I sold none ;-( I found this very interesting information. For comparison I tried this on a friend of mine book's Griffen's Daughter: Again it is quite clear when her sales are being made. 12/26/2008, 1/5/2009, 1/10,2009, 1/11/2009. This site even has the capability to compare your books to others. It is a great site.

CALCULATION MODEL CHANGES
Like search engines, who change their algorithms used to find content on web, I’m sure the calculation of Amazon Sales Ranks is revised from time to time so it is difficult to say which of the information I’m about to tell you about is “applicable” at the time of this blog. For instance, I found some data that was obviously old (for instance one post mentioned that rankings for books in the 100,000 – 500,000 range were only updated once a day but I personally saw this not be the case. In a 2008 post from Foner Books they state:

On October 14th, 2004
Amazon made the first major change to their ranking system
that I'd seen in five years. The new system is actually more transparent than
the old system. The new rank is preceded by a # and appears right on the sales
page for any book. There are two main differences between the old system and the
new system. First, the new system includes sales of both Marketplace books (used
and new) and e-books. Second, the new system is based almost entirely on "what have you done for me lately." Historical sales only have a small impact on the
decay rate.

The next few sections are taken not from my “personal” observations but from posts by others. I tried to indicate of the data when possible.

ROUGH ESTIMATE OF SALES
On August 10, 2006 the author of “Math You Can't Use: Patents, Copyright, and Software” (one of those “bigger minds” that I mentioned) wrote an automated script to take sales ranks every 20 minutes. After some analysis here is what he concluded:

1-10	Oprah's latest picks
10-100	The New York Times's picks
100-1,000	topical rants by pundits/journalists,"classics"
1,000-500,000	everything else (still selling)
500,000+	everything else (technically in stock)

SALES RANK TO COPIES SOLD PER WEEK
In a 2008 post from Foner Books they presented the author proposed a logrithmic chart that allows you to approximate the numbr of copies sold per week. If we use the sales rank of approximately 60,000 from the example above then this graph estimates about 10 copies per week are selling. He mentions: "I've seen ranks as low as the mid-three millions for books that have sold a single copy, the line would be completely vertical by around 4,000,000. I cannot stress enough that checking the rank twice and looking at this graph means nothing. You have to get an average rank for at least a week for it to have any meaning at all."

EFFECTS OF TAGGING, REVIEWS, and PAGE VIEWS
Whether good reviews and number of page hits have a direct effect on the sales rank formula is unclear. I have heard that adding tags can "temporarily" effect the ranking, again I'm not sure if this is true or not. My guess is that any effect of "tagging" is short lived and the momentarily spike of good ranking corrects itself.

SOME PARTING THOUGHTS
The most important thing to remember about your sales rank is its temporary and relative nature. The Amazon rating is more like a popularity contest than the litmus test for a book’s success. The number you see on the page is merely how you’re selling compared to other titles in a very brief period. Two or three purchases of the same book within an hour can send a title skyrocketing up the rankings. Sure it’s exciting to leave a few thousand of your competitors in the dust, but unless the buying continues at a good pace, you can slip from the higher rankings fairly quickly.

But in the end, the sales rank is meant to be, in Amazon.com’s words, merely “interesting.” Don’t sweat it if you can’t figure out why your number is exactly where it is. Instead, focus your energy on making your product page as informative and consumer-friendly as possible.