How to Measure for a Bifold Door

When ordering a bifold door it's important to understand how to measure the door opening. Use the guide below to assist you in gathering the correct measurements

You may also download this measuring guide

A - The first step is to measure the width of the door opening.

Measure from the inside of the finished door jamb on one side to the inside edge on the other side.

Measure the opening near the top, middle and bottom, and use the narrowest width measured.

B - The second step is to measure the height of the door opening. Measure from the inside of the finished door header to the top of the finished floor covering. Measure the opening near the left, middle and right, and use the shortest length measured.
Bifold doors will be prefit for standard sized openings. The right size door for you is the one with the whole number measurements closest (but not larger than) the width and height of your opening. The door will be made slightly smaller to allow for it to operate properly (see table below).

For openings of 48”, 60” and 72” widths, two (2) bifolds doors are used:

48” width use two (2) 24” bifolds
60” width use two (2) 30” bifolds
72” width use two (2) 36” bifolds

There’s no need to find a door with exactly the same prefit dimensions as the door being replaced. Different manufacturers use slightly different specs.
WIDTHS HEIGHTS
Nominal Actual Nominal Actual
24”
30”
36”

23-11/16”
29-11/16”
35-11/16”

78”
80”
96”
76-3/4”
78-3/4”
94-1/2”

Bifold door thickness, generally 1” or 1-3/8”, is a matter of design, style and aesthetics.