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
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.
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.
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.
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.
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.