If you’re writing a book proposal, one  important number to obtain is the number of books sold for any competitive or complementary books you plan to compare with yours.

Here’s a Book Proposal Secret: For the most part, you want to compare your book to bestsellers and backlist books (books that have been in print a long time). You want agents and publishers to associate your book with other books that have sold well. Don’t compare your book to one that sold 200 copies.

And publishers love to see actual numbers of book sales to get a flavor for it. Sure, they could look up the numbers on Ingram, but they don’t really have time for that when they’re first assessing a book proposal–you want to make an impact right away with big numbers.

So, how do you get those numbers? You can’t get them from Ingram anymore (unless your friends in publishing look them up for you). But you can do a number of things:

1. Search for the book on Amazon and “look inside the book” at the front and back covers (blown up version if you can) to see if the cover boasts number of copies sold. Yes, this is a long shot, but once in a while you hit the jackpot. Likewise, you can also check the Publishers Weekly review and other reviews to see if they mention sales.

2. Do a Google or search engine search for specific keywords, such as “book title millions copies sold” or “book title new york times bestselling.” Think up as many combinations of these keyword searches as you can–one may hit pay dirt. Note the date of the posting, review or article. Say, in your proposal, “As of xxxx date, the book sold x million copies.”

3. Go to the bookstore and see if the actual book mentions the number of copies sold or bestseller status.

4. Some people include Amazon ranking or Barnes and Noble ranking when comparing books. It’s not a terrible number to use but it can be misleading since those rankings change by the minute–and a book with a high ranking one hour may be much lower the next hour for various reasons. I usually stay away from mentioning these.

5. If the book was a bestseller on any particular chart, certainly mention this. Also mention how long the book has been in print if it’s a classic. This implies your book has backlist potential, too.

And, one more thing when comparing your book to bestsellers:  Some authors just mention what’s different about their book. Don’t get caught in that trap. Stress both similarities and differences. You want agents and publishers to think: “This book has much in common with the bestsellers that make it likely to be a bestseller, but it also has some unique selling points that differentiate it and make it a valuable addition to the books that are already out there.”

Good luck with your book proposal! If you have any other ways you’ve researched sales for competitive titles, please do share! And I’m happy to answer other book proposal questions you may have as well–just share your question as a comment.