I am planning on building a bookcase and some previous attempts have resulted in shelves that are too deep for most books.
Is there an average depth that would work best? For example would a 9-inch deep shelf fit for most books and standard paperbacks (8.5 x 11)?
I walked around my existing book collection with a tape measure and determined that 9.5" inches will work for a) paperbacks b) average size other books c) binders.
Another possible option would be to query the Library of Congress (via API?) to see what the average/median dimensions are for books in the past 30 years.
I went with a 9.5 inch deep bookcase. This works well for most of my books and optimizes the usage of the 4'x8' sheet of plywood.
Note: Cutting 4x8 sheets of 3/4" plywood on a portable tablesaw is very challenging especially when the lumber yard's table saw is broken!