The paperbacks are stacked two deep, the tall art books are lying flat on top because they will not stand up, and the one shelf that holds the cookbooks has started to bow in the middle. Most bookcase problems come down to three numbers nobody checked before buying: the height of the unit, the depth of each shelf and the gap between shelves.

This guide answers the questions people ask most when choosing a bookcase, using real sizes from the solid timber bookcases in our range. If you already have a tape measure in hand, you can browse our bookcases and filter them by size as you read.

What sizes do bookcases come in?

Bookcases fall into four broad groups, and each suits a different spot in the house.

Every size above comes from the product pages of bookcases we currently sell. Use the table to narrow down the type first, then check the exact size of the model you like.

How tall should a bookcase be?

Start with the ceiling and the people using it. A tall bookcase of 180 to 200 cm holds the most books for the floor space it takes, which makes it a natural fit for a study or a living room wall. The Humbie Large stands 190 cm tall with five shelves and two drawers at the base, and the Beverley in solid ash reaches 200 cm.

Go lower when:

• the bookcase sits under a window or behind a sofa
• children need to reach their own books
• you want to use the top as a surface for lamps, plants or photos

Anything around 110 cm tall or less stays at a comfortable reach for most adults and keeps a room feeling open. If you like the look of a tall unit but your ceiling is low or sloped, a slim tall bookcase takes the height without the visual bulk.

How deep should bookcase shelves be?

Depth is the measurement people skip, and it is the one that decides whether your books fit. As a rough guide:

• Most paperbacks are around 11 to 13 cm deep, so a 23 cm shelf holds them with room to spare.
• Standard hardcovers are usually 15 to 17 cm deep and fit comfortably on shelves of 30 cm or more.
• Large art, travel and coffee table books can be 25 cm deep or more, so look for 35 to 40 cm shelves if you own many of them.

In our range, the Apolda and Kasai are 23 cm deep, which keeps them slim enough for a hallway. Many of our tall bookcases, such as the Humbie and the solid oak Warburg, are 32 cm deep, and the Beverley and Vaja are 35 cm. The Zetland Large goes to 40 cm, with a lower shelf that takes storage baskets or oversized books. Deeper is not always better: on a very deep shelf, paperbacks disappear behind each other and end up stacked two rows deep.

How much space should there be between shelves?

Measure the tallest books you plan to keep, then allow 2 to 3 cm above them so you can tilt a book out with one finger. Around 25 cm between shelves suits most paperbacks and standard hardcovers. Taller art books and folders need 30 cm or more.

Two features make this easier to get right:

• Adjustable shelves. The Vaja has adjustable shelves, and the Myrland offers three height levels on each shelf, so you can move shelves as your collection changes.
• Mixed shelf heights. The Apolda gives every shelf 32 cm of height, and the Orvieto mixes taller and shorter openings for books, boxes and toys.

Put the heaviest books on the lowest shelves. It keeps the centre of gravity low and stops the upper shelves carrying more weight than they need to.

What size bookcase fits a small room or a narrow wall?

Look at width first and depth second. For a gap beside a desk, a door or a fridge, a slim bookcase gives you shelf space without blocking the walkway. The solid oak Warburg is only 30 cm wide and comes in 111, 145 and 180 cm heights. The Humbie Slim is 55 cm wide and 190 cm tall, and the Apolda comes in 40 or 60 cm widths at just 23 cm deep.

For a corner, the Nerola is a rotating bookshelf with a 40 by 40 cm footprint that turns a full circle, so you can reach books on every side without moving the unit. The Orvieto extends from 112 to 157 cm wide and turns into an L shape to fit a corner.

When is a low bookcase the better choice?

A low bookcase works as storage and as a surface at the same time. It fits under a window, behind a sofa or along a hallway, and it keeps books within reach of children.

• The Myrland is 150 cm wide and 93 cm tall, with 8 or 10 cubes, and its removable back panel lets it work as a room divider.
• The Renwick Small is 110 cm wide with two shelves above two drawers, a good size for a child's room.
• The Zetland Small is 123 cm wide and 105 cm tall, with four open shelves.

Low units also leave the wall above free for art or a mirror, so a room can hold plenty of books without feeling closed in.

Should you choose open shelves, glass doors or a modular system?

Open shelves are the easiest to use and show off the spines. Glass doors keep dust off, which matters for collectible books and anything you do not read often. The Odense has full height glass doors and comes 42.5 or 85 cm wide at 200 cm tall, and the Vaja comes with glass doors in its 45, 80 and 90 cm widths.

Modular shelves suit people who expect to move house or add to their collection. The Kasai comes in 68.5 and 102 cm widths and three heights up to 181.5 cm, and each unit can stand upright or on its side. The Asele units share one 75 cm height, so they line up neatly in widths from 50 to 130 cm, in an oak or walnut colour.

All of these are solid timber, so the shelves hold heavy books well over the years. If you are still deciding between solid wood and flat pack, our article on why a solid oak bookshelf is worth it covers durability and value in more detail.

Do you need to fix a tall bookcase to the wall?

Yes, it is a good idea for any tall bookcase, especially in homes with young children. A loaded bookcase can tip if someone climbs it or pulls on an upper shelf, and in New Zealand an earthquake can topple an unfixed unit. The Natural Hazards Commission's guide to securing tall furniture and bookshelves explains how to fix them to the wall studs with straps or metal angle brackets. Fix into a stud rather than plasterboard alone, and keep the heaviest books on the bottom shelves. If you rent, the same guide notes that landlords must allow minor changes such as anchoring tall, heavy items, so talk to your landlord first.

Which bookcase size is right for your room?

• A study or living room wall with plenty of books: a tall bookcase of 180 to 200 cm, around 32 to 35 cm deep.
• A narrow gap, hallway or small apartment: a slim bookcase 30 to 60 cm wide, or a rotating unit for a corner.
• Under a window, behind a sofa or in a child's room: a low bookcase around 90 to 110 cm tall.
• Large art books or baskets: shelves 35 to 40 cm deep with 30 cm or more between them.
• A collection that keeps growing: modular shelves you can add to later.

Once you have the height, width and depth written down, check them against the product page of the model you like. Each one lists the exact dimensions for every size option, so you can confirm the fit before you decide. If you would rather keep your books behind glass and away from dust, have a look at our glass door display cabinets as well.

What else do people ask about bookcase sizes?

What is the standard size of a bookcase?

There is no single standard, but most tall bookcases are 180 to 200 cm high and 30 to 35 cm deep. Widths vary more, from 30 cm slim units to 100 cm wide models. Low bookcases usually sit around 90 to 110 cm tall.

How deep should a bookshelf be for hardcover books?

Standard hardcovers fit comfortably on shelves 30 cm deep or more. For large art or coffee table books, choose 35 to 40 cm. Paperbacks only need about 23 cm.

How wide should a bookcase be?

Measure the wall and leave some space at each side so the bookcase does not look squeezed in. Slim units of 30 to 60 cm suit narrow gaps, while 80 to 100 cm suits a main wall. For a very long wall, two matching bookcases side by side often look better than one extra wide unit.

What is a good bookcase for a child's room?

A low bookcase around 90 to 110 cm tall lets children reach their own books and keeps the weight low. Choose rounded or chamfered edges where you can. Fix any taller unit to the wall.