How can I find out how many copies an album has sold?

How can I find out how many copies of a book were sold?

• I would like to find out if there is a resource, which will allow me to find out how many copies of a book has been sold. For example If I searched by title, or ISBN number, it would give me an estimate

• Answer:

  Depending on timing, the best available source for this information is the publisher of the book, which has data on sales into the retail/wholesale market, but not consumer purchases.  The numbers can also change based on returns (retailers and wholesalers have the right to return unsold copies of the book). The second best source is Nielsen Bookscan, especially if you're looking for time sensitive info and consumer purchase info (in which case, Bookscan is better than the pub). Unfortunately, neither of these sources is available to the public, even with payment. Also, I'm unclear if Bookscan has resolved the ebook issues, but they used to have problems tracking these formats.  Subscriptions to Bookscan can be purchased that allow you to look individual titles and see sales by channel and estimated total sales (they don't get reporting for all sales.)  Amazon is so big at this point that their sales rank can be a good relative ranking of titles.