How do I measure my garage opening for a new door?
Take five measurements: opening width and height (jamb to jamb, floor to header), side room on each side (3.75 inches minimum for standard track), headroom above the opening (10 inches minimum with an opener, ideally 12+), and backroom depth (door height plus 18 inches). Measure in three spots each and record the smallest number.
The five numbers, in order
| Measurement | How to take it | Minimum needed |
|---|---|---|
| Width | Inside jamb to inside jamb, at floor, middle, and top | Matches door width exactly |
| Height | Floor to underside of header, at both sides and center | Matches door height exactly |
| Side room | Jamb edge to nearest wall or obstruction, each side | 3.75 in standard, 5.5 in for some torsion setups |
| Headroom | Top of opening to ceiling or lowest obstruction | 10 in with opener, 4.5 in with low-headroom kit |
| Backroom | Opening into the garage along the ceiling | Door height + 18 in, more for some openers |
Garage doors are ordered to the finished opening size, not smaller like an interior door. A 16x7 door goes on a 16-foot-wide, 7-foot-tall opening; the stop molding and weather seal handle the overlap. If your numbers land oddly, like 15 feet 10 inches wide, do not round. Odd sizes are orderable from DoorLink and CHI and cost little more than stock sizes.
Where measurements go wrong in OKC homes
- Sloped or heaved slabs. Clay soil movement across the metro, especially in Moore and south OKC, tilts garage floors. Measure height at both jambs; a difference over an inch means the bottom seal or a slab grind has to make up the gap.
- Ceiling obstructions. Furnace ducts, water heaters on platforms, and storage racks eat headroom and backroom. Measure to the lowest thing hanging down, not the drywall.
- Out-of-plumb jambs. Homes from the 60s and 70s in Bethany and Warr Acres often show a half inch or more of lean. Note it; the installer plumbs the new tracks regardless, but the framing may need attention, which we cover in when jambs need replacing.
- Measuring the old door instead of the opening. The old door can be the wrong size for the hole it lives in. Trust the opening.
When to let us measure instead
Your tape-measure numbers are plenty for a phone quote and a ballpark price. Before any door is ordered, though, a tech takes final measurements on site, because a door ordered wrong is a two-to-six-week factory do-over, as explained in door lead times. Site measure is part of our free estimate for any installation, and if headroom or side room comes up short we will spec the track hardware that fits, including low-headroom options. Call (405) 247-0336 and read us your five numbers; that is genuinely all it takes to start.
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Related Questions
Can my garage door opening be widened for a bigger door?+
Yes. A framing contractor installs a longer header and reframes the jambs, then we hang the wider door. Budget for structural work plus the door, and expect a permit in most metro cities. Read the full answer →
What are my options if my garage has low headroom?+
Special low-headroom track hardware works down to about 4.5 inches of clearance, and rear torsion conversions go tighter still. Pair it with a wall-mount jackshaft opener and the ceiling stays completely clear. Read the full answer →
Can you install a garage door on a detached shed or shop building?+
Absolutely. Sheds, shops, and barns just need a framed opening with sound jambs and enough headroom for track. We install everything from 6-foot shed doors to 14-foot shop doors across the metro. Read the full answer →
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