Whether you are moving a home library, buying bookcases or building shelves into a wall, it helps to know how much space your books need. This calculator works out books per shelf, shelves and bookcases, and the weight each shelf has to carry.
Books per shelf
books per shelf = shelf width × fill rate ÷ average thickness
The fill rate leaves room for bookends, for leaning books and for new arrivals. Shelves filled to 100% are hard to use; 80 to 90% is comfortable.
A 30 in shelf filled to 85% with books about 1 in thick holds 25 books.
Average thickness
| Type | Typical spine |
|---|---|
| Mass-market paperback | 0.75 to 1 in |
| Trade paperback | about 1 in |
| Hardcover novel | 1.25 to 1.5 in |
| Art book, textbook | 1.5 to 2.5 in |
| Children’s picture book | 0.25 to 0.5 in |
The quickest way to estimate is to measure a meter or a yard of your own shelves and count the books on it.
Example
400 books at 25 per shelf need 16 shelves, or 4 bookcases of 5 shelves. At 1 in each with an 85% fill, that is about 39 ft of shelving.
Shelf height and depth
- Most novels and paperbacks fit on shelves with about 10 to 11 in of clear height and 8 to 10 in of depth.
- Hardcovers and art books need 12 to 15 in of height and up to 12 in of depth.
- Adjustable shelves make it easy to fit mixed sizes.
Weight and sag
Books are heavy. At about 1 lb per book, a full 30 in shelf carries 25 lb, and a whole bookcase over 100 lb. Particleboard and long shelves sag over time; check your shelf with the shelf sag calculator, keep spans under about 30 to 32 in for 3/4 in particleboard, and anchor tall bookcases to the wall so they cannot tip over, especially with children around.
Moving books
Pack books in small boxes, about 1.5 cubic feet, so each box stays under 40 to 50 lb. One small box holds roughly 20 to 30 average books.