A standard bookshelf is 60 to 84 in tall, with shelves 10 to 12 in deep and 10 to 12 in apart. Keep a 3/4 in shelf to about 30 in between supports to stop it sagging.
A bookshelf that works is mostly about four numbers: how deep the shelves are, how far apart they sit, how wide each section is, and how tall the whole unit is. Here are the usual sizes, with the reasons behind them.
Standard bookshelf dimensions
| Dimension | Typical size | In mm |
|---|---|---|
| Total height | 60 to 84 in | 1525 to 2135 mm |
| Shelf depth | 10 to 12 in | 255 to 305 mm |
| Space between shelves | 10 to 12 in for most books | 255 to 305 mm |
| Width of one section | 24 to 36 in | 610 to 915 mm |
| Shelf thickness | 3/4 in (solid wood or plywood) | 19 mm |
Shelf depth
Most books are less than 10 in deep, so a shelf about 10 to 12 in deep holds them with a little room. A 1x12 board is 11 1/4 in wide in real size (see the lumber size chart), which makes it a very common choice for bookshelf shelves. Use deeper shelves only if you plan to store large art books or boxes.
Spacing between shelves
Books come in a few heights: mass-market paperbacks are around 7 in, trade paperbacks 8 to 9 in, and standard hardcovers about 9 to 10 in. Large art and photography books can be 12 in or taller. A spacing of 10 to 12 in fits the usual books, and you can leave one taller space for the big ones. Measure your own books before you cut.
How wide can a shelf be before it sags?
A shelf bends under load, and the longer it is, the more it bends. As a rule of thumb, a 3/4 in pine or plywood shelf carrying books should span no more than about 30 in between supports. Wider shelves need help: a 1x2 rail glued and screwed along the front edge, a center support, or a thicker board. Heavy books such as encyclopedias or art books need the shorter span.
How tall should it be?
Between 60 and 84 in is typical. Taller units hold more but are harder to reach and heavier. If you can reach the top shelf easily and your ceiling allows it, 72 in is a popular height. Tall bookcases can tip, so anchor them to the wall with straps or brackets into studs, especially in homes with children or pets.
A five-shelf plan with the numbers worked out
Our Five-Shelf Bookshelf (plan PS-11) is 30 in wide, 11 1/4 in deep and 60 in tall (762 x 286 x 1524 mm), built from pine or poplar 1x12, 1x4 and 1x2. The plan gives the shopping list, a cutting diagram and the Square Checks to measure as you build. See the Five-Shelf Bookshelf plan page. Our plans are modeled and checked in 3D and have not yet been built and tested.
Frequently asked questions
What is the standard depth of a bookshelf?
Most bookshelves have shelves between 10 and 12 inches deep, which holds most books with a little room to spare.
How far apart should bookshelf shelves be?
About 10 to 12 inches for most books. Leave a taller space for large art books.
How wide can a bookshelf shelf be without sagging?
As a rule of thumb, keep a 3/4 inch pine or plywood shelf to about 30 inches between supports, and add a front rail or center support for wider spans or heavy books.
What size is a 1x12 board?
A 1x12 measures 3/4 inch by 11 1/4 inches in real size.
Should I anchor a tall bookcase?
Yes. Tall bookcases can tip over, so anchor them to wall studs with straps or brackets.
Build a five-shelf bookshelf
Plan PS-11 has the shopping list, a cutting diagram and the Square Checks, with every dimension worked out.
See the plan