Bookcase Dimensions: Standard Sizes, Shelf Spacing and Capacity

Standard bookcase dimensions by number of shelves

Bookcase height goes up in steps of roughly 12 in per shelf, because that spacing fits most hardcovers. Width and depth are independent of height: most ranges offer each height in two or three widths, all at the same depth.

"Shelves" counts every surface you can put books on, including the bottom. Some brands count the top as well, so a "5-shelf" bookcase may have only four interior shelves. Check the height and the spacing instead of the count.

2-shelf 30 × 30 in3-shelf 30 × 40 in5-shelf 30 × 70 in6-shelf 30 × 79.5 in

Metric bookcase sizes

European bookcases are built to round centimeter sizes: widths of 40, 60, 80 and 100 cm, depths of 28 to 35 cm, and heights of about 80, 106, 150, 180 and 200 cm. Two IKEA ranges are so common that they work as reference sizes.

BILLY's 28 cm (11 in) depth holds almost any novel and most hardcovers but not large art books. KALLAX's deeper cubes take records, binders and storage boxes, and the 13-inch openings fit standard 13-inch fabric bins.

Shelf depth and spacing for different books

Size the shelves to the books, then the bookcase to the shelves. Allow about 1 in (2.5 cm) above the tallest book so you can tip it out, and an inch of depth so spines don't overhang.

Adjustable shelves on 32 mm (1¼ in) hole spacing are the norm, so you can fine-tune each shelf. A practical layout for a 72-inch bookcase: one 15-inch bottom shelf for oversized books, three 11-inch shelves for hardcovers and one 9-inch shelf at the top for paperbacks.

How many books fit on a bookcase

Books average about 1 to 1.5 in thick. That gives roughly 8 to 10 hardcovers or 12 paperbacks per foot of shelf. The usable width of each shelf is the outside width less two side panels, about 1.5 in in total.

Multiply by the number of shelves. A 36-inch, 5-shelf bookcase holds about 115 to 145 hardcovers. If the collection keeps growing, plan 20 to 25% empty space so you can add books without reshuffling every shelf.

Shelf span and sagging

Books are heavy: a foot of hardcovers weighs roughly 15 to 25 lb (7 to 11 kg). The longer and thinner the shelf, the more it bows under that load, and the bow becomes permanent in particleboard and MDF over months. These are widely used limits for a shelf fully loaded with books:

This is why so many bookcases are about 30 to 32 in wide with 3/4-inch shelves (BILLY's shelves span about 76 cm), and why 48-inch bookcases have a center divider. A 1 × 2 in hardwood strip glued to the front edge of a shelf roughly halves its sag.

Fitting a bookcase into a room

• Walkway: an 11 to 12 in deep bookcase with 36 in of clear floor in front is comfortable to browse. In a hallway, a 9 to 10 in deep paperback case keeps more of the passage free.
• Under windows: sills are often 30 to 42 in above the floor, so 2- and 3-shelf units (28 to 40 in) fit beneath them.
• Built-in look: leave 2 to 3 in between a 79½-inch BILLY and an 8-foot (96 in) ceiling for tilting it upright during assembly, or use a height extension.
• Behind a desk: keep at least 36 in between the bookcase and the desk edge so the chair can roll back. See the desk dimensions guide for full clearances.
• Media: a bookcase is too shallow for most TVs and AV gear, which need 16 to 20 in; see TV stand sizes.

For glass-front cabinets to show collections rather than store books, see the display case size guide, and for closed storage the cabinet dimensions guide.

Anchoring a tall bookcase

A loaded bookcase is top-heavy, and a child climbing the shelves can pull it over. The US federal tip-over rule for clothing storage units (16 CFR part 1261) specifically excludes bookcases, so there is no mandatory stability test for them and many are sold with only a basic wall strap. Fit the strap to a stud or with wall anchors rated for the wall type, load the bottom shelves with the heaviest books, and anchor any bookcase taller than it is wide.

Frequently asked questions