How to measure a garage door opening

A garage door is sized to the finished opening, and it also needs room around the opening for tracks, springs and an opener. Five measurements tell us almost everything. Use a steel tape and measure in inches.

1. Width

Measure the finished opening from the inside of one jamb to the inside of the other. Measure at the bottom, middle and top, and send us the largest number.

2. Height

Measure from the floor to the underside of the header in the center of the opening. If the floor slopes, measure at both sides too and tell us the difference.

3. Headroom

Measure from the top of the opening up to the ceiling — or to the lowest thing in the way, such as a beam, pipe or light. Standard sectional tracks need a minimum amount of headroom; high-lift and vertical-lift tracks need much more. Low headroom doesn’t rule a door out, but it changes the hardware.

4. Side room

Measure from each side of the opening to the nearest wall or obstruction. The vertical tracks mount here, and a wall-mount opener needs extra space on one side.

5. Backroom (depth)

Measure from the opening straight back to the far wall or the first obstruction. A standard track runs back roughly the height of the door plus a bit more; an opener adds to that.

Before you send them

• Take a photo of the opening from inside and outside.
• Note what’s on the ceiling: beams, lights, ductwork, a sloped ceiling.
• Tell us whether there’s power near the opening for an opener.

We confirm the exact clearances your door and track need in your quote. If anything is tight, we’ll suggest the right track option — or come out and measure.