Related tools
← Back

Shelf Spacing Calculator

Equal openings between shelves, plus how many brackets you need.

Bottom to top of the area the shelves live in (e.g. counter to ceiling)

1.5" for a chunky floating shelf

Even openings between shelves, worked out from your actual shelf thickness — because shelves take up space, and forgetting that is what makes the bottom opening come out short.

How it works

The shelves themselves occupy part of the height, so they are subtracted before the space is divided: opening = (total height − (shelves × shelf thickness)) ÷ (shelves + 1). As with board spacing, there is always one more opening than there are shelves.

Example

A 72-inch bookcase with four 3/4-inch shelves: the shelves take up 3 inches, leaving 69 inches across five openings — about 13 3/4 inches each.

Tips & common mistakes

  • Measure what is going on the shelves before you space them. Perfectly even shelves that will not fit a single one of your books are a beautiful, useless piece of joinery.
  • It is often better to make the bottom opening deliberately taller for big items and space the rest evenly. Even spacing is a means to an end, not the goal.
  • Remember the shelf thickness. Four 3/4-inch shelves eat a full 3 inches of height, and people routinely forget this and end up with a short bottom shelf.
  • For anything over about 30 inches wide, plan a center support. A shelf that sags in the middle is the most common shelving failure there is.

Frequently asked questions

How far apart should shelves be?

12 to 15 inches suits most books and general storage. Go to 15 or 16 inches for larger items, and 10 to 12 for paperbacks or spice jars.

How do you space shelves evenly?

Subtract the combined thickness of all the shelves from the total height, then divide by the number of shelves plus one. That gives an equal opening above, below, and between every shelf.

How wide can a shelf be without sagging?

About 30 to 32 inches for a 3/4-inch board carrying books. Beyond that, add a center support or use a thicker board — sag is permanent once it sets in.