For Authors

Calculating Book Sales from Amazon’s Sales Rank (ASR)

In the article Using Amazon’s Sales Rank System we discussed how to use Amazon’s search engine and the Amazon Sales Rank (ASR) to compile a bibliography of books for use in the “Competing Books” segment of your nonfiction proposal or for a “Comparative Book Survey” to accompany your fiction manuscript submission.

Reporting actual copies sold of the selected books provides maximum impact for your submissions. Even though “copies sold” data is difficult to find, you can calculate a useable number with the ASR.

Can accurate “copies sold” data be calculated from the ASR? The simple answer is, “No!” But thanks to Morris Rosenthal of Foner Books, reasonable estimates can be made.

These caveats must be understood before discussing how this is done:

  1. An ASR is for one edition (ISBN number) of an author’s title and does not reflect previous releases in other editions. Obviously the commercial viability of that title needs to reflect the sum of retail sales from all editions – hardcover, trade paperback, mass-market paperback, and special editions. The total sales computation formula compensates somewhat for this.
  2. An average of two month’s ASR’s taken at least three times weekly will give a much more accurate ASR, particularly for recent releases.
  3. There are large variations between retail sales computed using the ASR and actual retail sales from A. C. Nielsen BookScan in those few instances where this data is available.

Morris Rosenthal developed the Book Sales vs. ASR Graphs shown in . The first graph plots Books Sold Daily vs. ASR 1- 1,000. The second graph plots Books Sold Weekly vs. ASR 1,000 – 100,000.

Since Amazon reports only on its own sales, a method must be developed to determine total sales through all retail sellers. Rosenthal feels that the $16.8 billion estimated by the US Census Bureau for 2007 retail book sales is a good $10 billion lower than total book sales estimates from various industry surveys. Therefore:

Total U. S. Book Sales ($26.8 billion) / Amazon 2007 Book Sales ($4.63 billion) = 5.79 Amazon book sales from the graphs x 5.79 = (approx.) Total Retail Sales/Year

Amazon factors sales figures for the five previous years into the ASR, so Total Retail Sales/Year x 5 = Total Potential Sales.

Total Copies Sold From Graph #1:

Sales/day x 365 days x 5.79 Total Sales Ratio x 5 years = (approx.) Total Copies Sold.

Total Copies Sold From Graph #2

Sales/week x 52 weeks x 5.79 Total Sales Ratio x 5 years = (approx.) Total Copies Sold

“Total Copies Sold” computed with this method always produces a lower number than A.C. Neilsen BookScan figures, sometimes by a factor of over two. Therefore, anyone using these formulas to compute “Total Copies Sold” can rely on the fact that the number, when used for planning or for comparison, is always conservative. Rosenthal’s graphs are easy to pick up from the website and to enlarge for easier reading.

Ironically, the Nielsen BookScan data is available at most Publishers, but editors seldom do the research. Now you can produce reasonable sales data for them to use when evaluating your book proposal or manuscript.

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