Garage Door Rough Opening: Chart and How to Measure

By the Garage Sized team · Updated October 7, 2026 · Clearances from door makers’ manuals and guides · Rough openings from the framing rule for 2× jambs

The garage door rough opening means two different things depending on who says it. To a framer it is the hole in the wall framing. In a door maker’s manual it usually means the finished opening between the jambs, which is the same size as the door. This page gives both numbers for every common size, shows how to measure an opening you already have, and lists the room the tracks, springs and opener need around it. For the full list of door sizes, start with our garage door sizes guide.

Rough opening vs finished opening

Three openings matter, and they are a few inches apart:

• Rough opening: wall framing to wall framing, and floor to the underside of the header. This is what a framer builds. Angi says it should be 3 in wider and 1½ in taller than the door.
• Finished opening: jamb face to jamb face, and floor to the underside of the head jamb. DASMA, the door makers’ trade group, defines opening width as the “distance between jambs”. This is the door size. Amarr says the opening “is the same size as your new garage door” (Amarr).
• Clear opening: the space between the stop molding. Stop molding is “usually nailed to the jamb, outside the door” (DASMA) and its flap seals against the door face, so the door is a little wider than the gap between the moldings. In a builder’s worked example, trim and weatherstripping take about 2¼ in from a 9 ft door’s opening, leaving 105¾ in between the weatherstripping (Ask the Builder).

The extra 3 in and 1½ in are just the jamb lumber: two side jambs and one head jamb, each 1½ in thick. Clopay and Wayne Dalton call for 2 × 6 lumber around the opening, and DASMA recommends 2 × 6 as the minimum when a separate wood jamb is installed. No door maker we checked publishes the rough opening itself. The 3 in and 1½ in rule comes from framing guides: Angi, an installer’s chart from Seaside Garage Door Experts (“standard 2x lumber”), and Mid-Atlantic Door Group, an Overhead Door distributor, which puts it as door width plus the side jambs and door height plus the head jamb.

The terminology trap

Clopay’s installation manual labels the jamb-to-jamb opening “Rough opening (minus stop mold) = same size as door” (Clopay). It means the opening after the jambs. A framer who reads that line as framing size and then adds 1½ in jambs ends up with an opening 3 in narrower and 1½ in shorter than the door. When a door sheet gives an opening size, ask whether it is before or after the jambs.

Should you add an inch?

No. Home Depot’s buying guide says to measure the width “at its widest point” and “Add an extra inch on each side for safety” (Home Depot). CHI says to add an inch or two for “a half-to-one-inch overlap either side” (CHI). The overlap is real, but the stop molding already provides it when the door matches the jamb-to-jamb opening. Add an inch to each side of a jamb-to-jamb measurement and you order a door 2 in wider than the opening. Measure jamb to jamb and order that size.

Garage door rough opening chart

Where these numbers come from: the finished opening is the door size, as Clopay and Amarr state. The rough opening is our arithmetic, not a maker’s table: door width + 3 in and door height + 1½ in, for 1½ in (2×) jambs lining the opening, the rule in framing guides from Angi and Seaside. Seaside’s chart gives the same numbers for every size here. With ¾ in (1×) jambs the rough opening is 1½ in wider and ¾ in taller than the door, and some builders frame at the door size with no jambs (Seaside). Framers: confirm with the install sheet for the door you are buying before you cut.

The two most common single-door sizes work out like this. An 8 × 7 door needs a rough opening of 99 × 85½ in (8 ft 3 in × 7 ft 1½ in) with 2× jambs. A 9 × 7 needs 111 × 85½ in.

Two sizes need more care. For 10 × 10, Seaside notes that published charts disagree the most, and that some list 10 ft 9 in × 10 ft 3 in, so ask your door supplier. For a 12 ft door, the harder question is the header over the wider span. Seaside’s rule for any header: it “is sized by what is above it and how far it spans, not by the door under it”, and the number “belongs to your plan, your building official or an engineer”.

If your jambs are not 1½ in thick, use the same logic: rough width = door width + 2 jamb thicknesses, rough height = door height + 1 jamb thickness. There is no jamb at the floor.

How to measure a garage door opening

You need a 25 ft tape and a ladder (Overhead Door). Write each number down in inches. These are the six measurements Raynor asks for (Raynor lists headroom before side room):

1. Width. Measure jamb face to jamb face, not stop molding to stop molding, at the bottom, middle and top. If the three numbers differ, a jamb is out of plumb or bowed. Makers want plumb jambs and a level header (Wayne Dalton), so fix that before you order.
2. Height. Measure from the floor to the underside of the head jamb at both sides and the middle. Garage floors slope, so use the smallest number.
3. Side room. Measure from each side of the opening out to the nearest wall or obstruction. The vertical tracks need 3 to 3¾ in, depending on the maker. Clopay also wants 4½ in on each side above the opening for torsion springs, and Overhead Door says to allow up to 6 in for the vertical track. A wall-mount opener needs 8½ in on its side (Garaga).
4. Headroom. Measure from the top of the opening to the lowest thing above it: ceiling, beam, pipe, duct, light or opener rail. Torsion springs need 12 to 13½ in, extension springs 10 to 11 in, and a ceiling opener 2 to 3 in more. Less than that? See low headroom garage doors.
5. Backroom. Measure from the door wall straight back to the first obstruction at ceiling height. DASMA measures it from the door mounting surface. A 7 ft door needs about 102 to 110 in without an opener and 123 to 134 in with one (see backroom).
6. Obstructions. Note entry doors, attic stairs and lights near the opening or under the track path. Raynor counts anything that would interfere with the track or the door.

Minimum room by maker

The makers agree on what to measure but not on the numbers: side room and headroom differ by up to 1½ in, backroom by 8 in or more. Clopay and Wayne Dalton figures are from their install manuals, Amarr and Raynor figures from their measuring guides. Plan for the larger one unless you know who is making your door.

Sources: Clopay installation manual, Amarr, Wayne Dalton torsion and extension manuals, Raynor. Clopay’s FAQ asks for 5½ in of side room with its EZ-SET extension springs, and its track guide gives door height + 16 in of backroom. Headroom figures are for 12 in radius track. Garaga also lists 12 in for torsion springs and adds 2 in for an opener.

Backroom: how far back the tracks and opener reach

When the door opens, it rolls back and lies flat under the ceiling, so the tracks run back a little farther than the door is tall. A ceiling opener reaches farther still, because its motor sits behind the open door.

The + 18 in rule is from Clopay and Amarr, and Wayne Dalton’s table gives the same 102, 114 and 138 in. Opener lengths: Chamberlain (range across its models), Wayne Dalton manual (125 in for doors up to 7 ft, 137 in up to 8 ft, 168 in from 8 ft 1 in to 10 ft). Raynor and Amarr columns are door height plus each maker’s allowance.

For a standard 7 ft door with an opener, keep about 11 ft (134 in) clear behind the door wall and you meet every figure above. For a 10 ft door, keep about 14 ft (170 in) clear. Chamberlain says to measure from the header wall back into the garage.

Framing a new opening

If you are building the opening, the door maker’s install sheet is the final word. The rough-opening size below is the framing rule; the rest comes from the makers’ manuals and DASMA:

• Frame the rough opening at door width + 3 in and door height + 1½ in if 1½ in jambs will line it (the framing guides’ rule; makers give only the finished opening, which equals the door). Size the header from your plans or building official.
• Line it with 2 × 6 jambs and a 2 × 6 head jamb, plumb, square and flush with each other (DASMA TDS 156).
• Run the jambs up past the opening to carry the spring hardware. Wayne Dalton wants them at least 12 in above the top of the opening for torsion springs. Angi suggests framing up “as high as the hardware will go”, often 18 in above the header.
• Add a 2 × 6 spring pad on the wall above the header at the center of the opening, for the torsion spring’s center bracket. Wayne Dalton says to drill pilot holes and not to attach it with nails.
• Keep the inside wall clear beside the opening (3 to 3¾ in for the tracks, 4½ in above the opening for the springs) and the ceiling clear for the headroom and backroom above.
• Tack the stop molding. Clopay says to nail it “temporarily but securely” so the installer can set it against the door.

Questions people ask