How deep should shelves be, and how far apart should they go?

The real dimensions of books, files, records, crockery and boxes, and why unequal shelf spacing that fits actual objects beats evenly spaced shelves that fit nothing.

Difficulty: beginner
Time: 15 min
Read: 4 min

Short answer

Depth: 200mm for paperbacks, 250 to 300mm for mixed books and box files, 320mm for vinyl, 350mm plus for kitchen and storage. Height: 250mm for paperbacks, 320mm for most hardbacks, 350mm for box files, 340mm for vinyl. Space them unequally to fit what you own — even spacing looks tidy on paper and wastes a third of the height.

Shelf spacing is usually decided by dividing the available height by the number of shelves, which produces a set of gaps that fit almost nothing well. Every category of object has a dimension, and building to those dimensions is both more useful and, oddly, better looking, because a shelf with 15mm of air above the books reads as intentional and a shelf with 120mm reads as unfinished.

Step by step

Measure what you actually own before deciding anything.The tallest book, the deepest file, the widest box. Ten minutes with a tape measure removes all the guesswork that follows.
Set the depth from the deepest thing, plus a little.Paperbacks 110 to 130mm deep, so a 200mm shelf is generous. Hardbacks and art books up to 250mm. Box files 250mm. LP records 315mm. Kitchen storage and appliances 350 to 400mm. Deeper is not better: every extra 50mm of depth increases the pull-out force on the top fixing and collects dust in front of the things you use.
Set the height from the tallest thing, plus 20 to 25mm.Paperbacks 200mm tall so allow 230 to 250mm. Standard hardbacks 240mm so allow 270. Larger hardbacks and cookbooks 300mm so allow 320 to 340. Box files 320mm so allow 350. LPs 315mm so allow 340. Anything more than that gap is wasted height.
Deliberately vary the spacing.Taller gaps at the bottom for the large heavy items, shorter gaps higher up for paperbacks and small things. It puts the weight low, which is better for the fixings and better for anything that might tip.
Leave one flexible bay if you can.One taller gap that will take anything, or a twin-slot bay that can be adjusted. It absorbs the objects that do not fit the plan, and there are always some.
Check the reach heights.Below about 400mm from the floor means kneeling. Above about 1800mm means a stool. Put the daily things between 750mm and 1500mm and the rarely used things at the extremes.
Allow for the shelf thickness in the arithmetic.Six shelves at 18mm is over 100mm of the available height gone. It is a common way to end up one shelf short of the plan.
Think about how it is loaded, not just what fits.A shelf you have to lift things over to reach the back gets used for the front 150mm only. A shelf at 2m gets used for things you never want again. Both are worth knowing before you build.

Tips

A shelf that is 25mm deeper than the books gives somewhere for dust and nothing else. Match the depth to the contents and the shelf looks better as well as holding better.
In an alcove, measure the width at every shelf height rather than assuming one figure — alcoves taper, often by 10mm or more over a metre.
For a display shelf rather than a storage shelf, deliberate empty space is the point. Those rules do not apply.

Common mistakes

Dividing the height evenly between shelves — It produces gaps that fit no common object. A third of the height ends up as air above things that are shorter than the gap.
Making every shelf 300mm deep because that is what the board came as — Deep shelves lever harder on the fixings and hide their own contents. Rip the board down to what the contents need.
Planning shelves for the things you intend to own — Measure what is currently in boxes on the floor. That is what will go on the shelf.

If it doesn't work

Books lie flat on top of each other because they do not fit upright

Cause: Shelf gap too small for the tallest volumes — Fix: One taller bay at the bottom for large books. Flat stacking doubles the weight per metre and is worse for the fixings as well as for finding things.

The shelves look empty even when full

Cause: Depth or height far exceeds the contents — Fix: Shallower shelves, or accept it and use the depth for two rows front and back with the rarely used items behind.

The top shelf never gets used

Cause: Above comfortable reach — Fix: Reserve it for seasonal and archival storage in labelled boxes, and put nothing there that is needed in a hurry.

Questions people ask

What is the standard shelf depth for books?

There is no standard, but 200mm suits paperbacks, 250mm suits most mixed collections, and 300mm covers large hardbacks and box files. Deeper than the books is wasted and makes the fixings work harder.

How high above the books should the shelf above be?

About 20 to 25mm of clearance is enough to get a book out comfortably. Any more is unused height, and you can usually gain a whole extra shelf across a tall run by tightening it up.

What spacing works for a kitchen or utility shelf?

350 to 400mm deep and 300 to 400mm apart handles most food packaging, appliances and stacked crockery. Keep the heavy things — crockery, tins, pans — on the lowest shelf.