If you are expecting book sales that will require mailing single copies, have your printer make a mock up of your book with the actual papers and page count prior to printing, and then weigh it. Then add an envelope and a mailing label -- and any other collateral items you are considering including in your orders. This is operations, my friends. And operations can make or break a publishing company (or any other type of company for that matter). Does it really matter?
Challenge: We completed a project wherein 75% of the books were sent out to individuals one at a time. The book weighed 15.2 ounces, but with the envelope, bookmark and label, the final weight was 16.1 ounces. That meant that rather than paying $2.41, he was paying $2.82 per piece. (see Media Mail pricing sheet). With a margin barely at $4 per book when he arrived, that was a pretty significant difference. Prior to working with us, my client had paid for the whole second pound on each package because of one stinking 10th of an ounce. In this case, he was already using the lightest weight envelope and a regular mailing label, and my client liked the papers used in his book, so we didn't want to change that. Did we have an option?
Solution: On the next printing, we cut off 1/8th inch off the height of the book -- and that did the trick. There are creative solutions to nearly every problem, and this was a great fix for a potential profit hog. In our case, the buyers didn't even realize anything was different, and my client's profit margin rose over 10% per sale.
Moral of the story: Consider how you will be selling and fulfilling your books, and make the shipping operation part of your initial planning process. Make sure your shipping costs reflect the actual weight of the book, and that you have thoughtfully considered whether or not your buyer values that extra fraction of an ounce over saving a little on shipping. It could be the difference between making a profit and losing money on books sold, depending on the buyer's terms.