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!

  • 2
    Not a great answer, but I'd go to a bookstore and measure what they have. Also, consider the books you will use it for. In a kids room, I'd make them extra deep.
    – JPhi1618
    Dec 4, 2015 at 17:03
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    How much deeper than "most books" have previous shelves been? Take that number and subtract it from your previous attempts' depth. That's your new number. The depth that "works best" is... the depth that works best, for you. FWIW all the Ikea bookcases are 11" total (so slightly less inside with the backing).
    – Jason C
    Dec 6, 2015 at 0:32
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    This is too broad the way it is written. You could measure all the the books you have and take an average for your depth. Nothing wrong with books sticking out a little bit.
    – Matt
    Dec 6, 2015 at 1:51
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    This is a rather old question that bubbled up from the depths, so this is too late for OP, but might help others: Head over to the Sagulator to determine if your shelves are thick enough to support the weight you expect to put on them and help calculate the distance between supports.
    – FreeMan
    Oct 5, 2016 at 14:48
  • For your last implicit question, search for "sheet" in the previous Q&A. For example: woodworking.stackexchange.com/q/10026/5572 (Your takeaway is that a table saw is not the best way to break down sheet goods. At least, not without a friend to help you.)
    – user5572
    Aug 31, 2020 at 14:32

8 Answers 8


12" deep shelves are too deep for most books, again most books. I would make the bookshelf a "breakfront", the 2 lower shelves 12" deep above a 4" base or toe space, and step the front back at the 30-32" height and make the remaining shelves, 8, maybe 10" deep.

  • Thanks @Jack - I am going to make the top shelves 9.5" to optimize my plywood usage.
    – John M
    Dec 8, 2015 at 17:37

"Most books" is far too broad. Books of what type? Standard paperpacks or oversized ones? Modern hardback novels or vintage/antique books?

Even assuming you mean regular paperbacks I don't think an average is the way to look at this. There may be a common, perhaps even typical, shelf depth for a bookcase but I've yet to see it myself, so an average of the various depths that are manufactured might result in a shelf as unsatisfactory (for some books certainly, perhaps even for all books) as your previous builds.

Surely the way to approach this is to measure your books and decide the clearance from the front that you like and bingo, you have your perfect depth? All that's needed after that is to build the bookcase accordingly.


Depends on your books. The ones I built last time used 1x12's; that's overkill but it does handle some oversized art books and lets me put two rows of paperbacks on a shelf (one upright, another tilted back in front of them).

Book sizes might vary by country, but a table of traditional sizes can be found at


And note that you want the shelf to be able to handle your larger books, not you average book.

  • 1
    According to This Old House, common default depth for single-depth built-in bookcase units is 11" to 12". I've seen barraster's bookcase units up to 16" deep; 20" for file-cabinet modules; subtract about an inch and a half to get interior dimensions; I've also seem them go shallower as part of a system which allows shallow units to be stacked above deep units to create a breakfront effect (though the commercially produced systems don't usually permit that kind of mix-and-match).
    – keshlam
    Dec 12, 2015 at 1:23

Standard bookshelves are 11 inches deep.


Woodbin.com has some good design resources for furniture, check out http://www.woodbin.com/ref/furniture-design/shelves/ they suggest 10-12" deep as a common standard, they also have some good information on how wide vs how thick your shelf stock is, etc.


I have book shelves from two European manufactures. One is 12 inches deep and the other in 12.25 inches deep. I think book shelves are built that deep to make it more difficult for them to tip over as the books are usually towards the back and the shelves are against a wall. The suggestion of a break front is a way to have it both ways.

  • 2
    to compensate for the 'wobbly' nature of a skinnier bookcase I just used some large brackets to anchor the bookcase into a stud.
    – John M
    Dec 15, 2015 at 16:07

I have always used 11 1/2 inches on all bookshelves I have made that are part of a standing bookcase. Over the last 40 years, I have probably made about a dozen different bookcases for family and friends. Sometimes I use hardwood veneer plywood and other times I have used solid hardwood such as Cherry or Walnut. For plywood shelves, I also put a hardwood (matching the veneer) edge on the front of the shelf which is about 1 1/4 inches. This gives the shelf strength to prevent sagging from heavy books. On solid hardwood shelves this is not necessary.

I would not go under 11 inches for a shelf though. In the photo below, one of my bookcases, solid Cherry, has shelves 11 1/4 inches deep. In the lower left corner is a boxed set of Calvin & Hobbes Collection and it extends over the shelf by about 1/4 of an inch. Other books on that shelf also come closer to edge. Today that bookshelf is overflowing, I built it about 3 years ago.

enter image description here


That breakfront comment was genius. I have to make a built-in for a sitting room off of a bedroom, and there is just 18" of space inside the windows on the back wall. The plan is to build base cabinets, with bookshelves sitting on top. The 18" is smaller than I would like for the base, especially since it defines the depth of the top, which will overhang, not the depth of the base cabinets.

By doing the breakfront, I can make the center portion as deep as I want, probably ~24", and recess the wings to fit the 18" depth. That will also give me deeper shelves above the center base cabinet, which will increase versatility. I'm starting on the design tonight.

As for the original question, let your aesthetic sense be your guide. Do you find a book's overhanging a shelf by just a bit, or even more, to be disturbing? Then I'd go the 11.25" route (1x12 boards) or do the full 12" or a bit more if you are using plywood cut to size. If you don't have books that would overhang a 10" shelf, I'd use that dimension, or something close to it.

The most problematic books are the large format ones. They can be 15" or more across. It makes no sense to build a shelf to accommodate them. They are called coffee table books for a reason. People don't put them on shelves. Still, in my base cabinet with shelves on top project, laying those books down with the spine out on the lowest level of the shelf structure, directly on top of the base cabinet top, is a useful and attractive way to store them.

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