🚪 Door Framing Calculator
Calculate rough opening size, header size, jack studs, king studs, and cripple studs for any door
| Door Nominal Size | Door Type | RO Width | RO Height | Header (2x4 Wall) |
|---|---|---|---|---|
| 24" x 80" | Interior | 26" | 82.5" | Doubled 2x4 |
| 28" x 80" | Interior | 30" | 82.5" | Doubled 2x4 |
| 30" x 80" | Interior | 32" | 82.5" | Doubled 2x6 |
| 32" x 80" | Interior | 34" | 82.5" | Doubled 2x6 |
| 36" x 80" | Interior / ADA | 38" | 82.5" | Doubled 2x6 |
| 36" x 80" | Exterior | 38" | 82.5" | Doubled 2x8 |
| 42" x 80" | Interior Wide | 44" | 82.5" | Doubled 2x8 |
| 48" x 80" | Double / French | 50" | 82.5" | Doubled 2x8 |
| 60" x 80" | Double / Barn | 62" | 82.5" | Doubled 2x10 |
| 72" x 80" | Double Wide | 74" | 82.5" | Doubled 2x12 |
| 9 ft x 7 ft | Garage | 110" | 86.5" | Dbl 2x12 / LVL |
| 16 ft x 7 ft | Garage (2-car) | 194" | 86.5" | LVL Beam |
| Door Width | Jack Studs (ea side) | King Studs (ea side) | Header Length | Cripple Studs (16" OC) |
|---|---|---|---|---|
| 24" | 1 | 1 | 29" | 3 |
| 28" | 1 | 1 | 33" | 3 |
| 30" | 1 | 1 | 35" | 3 |
| 32" | 1 | 1 | 37" | 3 |
| 36" | 1 | 1 | 41" | 4 |
| 42" | 1 | 1 | 47" | 4 |
| 48" | 1 | 1 | 53" | 4 |
| 60" | 2 | 1 | 65" | 5 |
| 72" | 2 | 1 | 77" | 6 |
| 108" (9 ft) | 2 | 1 | 113" | 8 |
| Header Type | Actual Thickness | Typical Span | Notes |
|---|---|---|---|
| Doubled 2x4 | 3" | Up to 3 ft (36") | Non-load-bearing interior walls |
| Doubled 2x6 | 3" | 3 – 4 ft (36"–48") | Standard interior & light exterior |
| Doubled 2x8 | 3" | 4 – 5 ft (48"–60") | Wide interior, standard exterior |
| Doubled 2x10 | 3" | 5 – 6 ft (60"–72") | Double doors, garage openings |
| Doubled 2x12 | 3" | 6 – 8 ft (72"–96") | Large garage doors; load-bearing |
| LVL Beam | Varies | 8 ft+ (96"+) | Engineer-specified; large openings |
Framing a rough opening for a door means you add space between the wall and the door jamb at the top and both sides of a pre-hung door. If you buy such door, the necessary rough opening size is written in the door’s details. It is much more simple to use pre-hung doors, because they ease the installation.
Image of door framed without the surrounding sheet rock well shows how the whole work operates
How to Frame a Rough Opening for a Door
When you build houses, the rough opening is usually around 2-1/4 inches wider than the door size. After the door is hung, you use shims to correctly position the frame. For instance, for a 28-inch door you need a 30-inch opening, and for a 36-inch door you require a 38-inch space.
If you know how to cut 2×4 wood and use a nail, you have everything necesary to do such work.
The jamb serves to give a precise and adjustable way to set the door. If you would bind the door directly to the wall, you could not correctly operate its swing. That would only cost more money and would give a bad result.
Even so, not every door has a frame. Currently you find doors without frames only in very old big castles or churches. A frame allows better mounting and control of the door.
Good framing must have Strong Tie brackets at the top and bottom of the studs beside the jamb. Permanent opening, closing or heavy doors can move the framing over time. It is also serious that the door header bear the burden of the wall.
If the wall is load-bearing, maybe you need provisional support until when the new header is set.
The frame is made when you lay the vertical bits, the header and the sill on a flat surface. You lay first the upper plate, then the studs, and finally the header with small studs below. Like this stays enough space for easily adding the trim.
If there are only drywall walls without internal structure, you must build the opening perfectly square before ending the drywall. Later the door and frame are set by means of screws, glue and caulk.
Occasionally, on little projects, you build all exterior walls and later cut the openings for doors. Even so, doing so requires careful planning, structural knowledge and good techniques to not weaken the wall or fail the inspection. Also the type of siding and the wall-structure affects how youbest frame those openings.
