Shelf Spacing Calculator

1. Enter the interior height of the cabinet, top to bottom of the opening.
2. Enter how many shelves you want between top and bottom.
3. Enter the shelf thickness; 3/4 inch is typical.
4. Read the equal opening between shelves and the shelf pitch.

Shelf spacing is the gap between shelves in a cabinet, bookcase or wardrobe. Even spacing looks tidy and is easy to lay out, but the shelves themselves take up height, so you cannot simply divide the cabinet by the number of shelves. Ignoring the shelf material is the quiet reason so many home-built bookcases end up with a slightly cramped bottom compartment.

The trick is to remove the total shelf thickness first, then divide the remaining clear space by the number of openings. That gives an equal, usable gap in every compartment, whatever the shelf thickness. It is a small piece of arithmetic that makes a real difference to how a finished piece looks: evenly spaced shelves read as considered and professional, while gaps that drift bigger or smaller up the cabinet catch the eye immediately, even to someone who could not say why the piece looks slightly off.

1. Multiply the number of shelves by their thickness for the total shelf material.
2. Subtract that from the interior height for the clear space.
3. Count the openings, which is the shelves plus one.
4. Divide the clear space by the openings for an equal gap.

Adding one to the shelf count matters: three shelves between the top and bottom create four compartments, not three. This is the mistake that trips up most first-time cabinet builders, and it is worth pausing on because the plus-one applies to the openings, not the shelves themselves.

A bookcase has a 60 inch interior and you want 3 fixed shelves that are 0.75 inch thick. The shelves use 2.25 inches of height, leaving 57.75 inches of clear space. Three shelves make four openings, so each opening is 57.75 divided by 4, about 14.44 inches. The centre-to-centre pitch is that plus the shelf thickness, around 15.19 inches. If those openings turn out too tight for what you plan to store, the fix is simply to drop a shelf and recalculate, which opens every compartment up at once while keeping them even.

Interior Height

The clear inside height sets the total space to divide between the openings.

Number of Shelves

More shelves make smaller openings and use more height in shelf material.

Shelf Thickness

Thicker shelves eat more height, so heavy-duty stock leaves less clear space.

What You Store

Books, files and appliances all want different opening heights, so equal spacing is not always ideal.

Equal openings in a 60 inch interior with 0.75 inch shelves.

For reference, a shelf for large books wants at least 12 inches; standard paperbacks fit in 8 to 9. This is why a bookcase built purely for even spacing sometimes needs a rethink once real books go on it, and why many makers leave the bottom opening a little taller for oversized volumes and box files.

Building a Bookcase

Lay out even shelves that look balanced and fit your books.

Drilling Shelf Pins

Find the pin positions for evenly spaced adjustable shelves.

Fitting a Cabinet

Divide a wardrobe or pantry into equal, usable compartments.

1. Forgetting Shelf Thickness

Dividing the height by the shelves ignores the wood they use, giving uneven gaps.

2. Miscounting Openings

Shelves create one more opening than their number; remember the plus one.

3. Ignoring What You Store

Equal spacing looks neat but may not suit tall and short items; adjust if needed.

4. Measuring Outside

Use the interior height, not the outside of the cabinet, for the clear space.

The spacing maths is exact for the height, shelves and thickness you enter. It divides the space equally, which is not always what the contents want.

Subtract the total shelf thickness from the interior height, then divide by the number of openings, which is the shelves plus one.

One more than the number of shelves. Three shelves between the top and bottom create four openings.

It depends on the books: large books want at least 12 inches, standard paperbacks fit in 8 to 9 inches of opening.

Yes. The shelves use up height, so subtract their total thickness before dividing the clear space.

The centre-to-centre distance between shelves, equal to the opening plus one shelf thickness.

Work out the equal opening, then set the pins at that spacing plus the thickness up the row of holes.

Not always. Equal spacing looks tidy, but tall and short items may call for different opening heights.

Use the interior height, the clear space inside the cabinet, not the outside dimension.

No. The calculator runs entirely in your browser and nothing you enter is stored or sent anywhere.

• Shelf (storage) (Wikipedia).
• Cabinetry (Wikipedia).
• Bookcase (Wikipedia).