Door rough opening

Rough opening calculator

Pick the door type, the width and the height. The drawing shows the door to scale next to a 5 ft 9 in (175 cm) person, with the rough opening dashed around it.

Door rough opening chart

The rough opening is the framed hole in the wall, measured from stud to stud and from the subfloor to the underside of the header. It is bigger than the door so the frame, called the jamb, and the shims behind it fit in.

Interior: Mastercraft interior rough opening chart (revised April 2019). Exterior: Masonite lists 34½ and 38½ in widths and 82½ and 98½ in heights; Therma-Tru gives 38½ × 82½ in for a 36 × 80 in door. "About" figures apply the same allowance to sizes the makers don't list.

Why 82½ in and not 82 in? Home Depot says the rough opening should be at least 2 in larger than the door, and Lowe's says openings are generally 2 in wider and taller (Home Depot, Lowe's). Mastercraft's chart asks for 82½ in for every 80 in door, ½ in more than that minimum. Framing to 82½ in gives room to shim the head jamb and to clear a thick floor. The width rule is the same in all three: door plus 2 in.

The door label is the slab size. A 32 in door is 32 in wide; once it is hung in its jamb, the clear opening you can walk through is about 30 in. Our standard door sizes guide covers slab sizes, the clear width and the code minimums.

Double and French door rough openings

For a pair of prehung interior doors, add 2 in to the width of the pair, or 2½ in if the pair has an astragal, the strip that covers the gap where the two doors meet. The height stays at 82½ in for 80 in doors.

Source: Mastercraft double prehung interior door rough opening guide. Exterior French doors and patio doors follow their maker's sheet.

Pocket door rough opening

A pocket door slides into the wall, so the opening has to hold the door twice over: once in the doorway and once in the pocket. Johnson Hardware's 1500 frame, the common kit for 2×4 walls, needs a rough opening twice the door width plus 1 in, and 4½ in taller than the door, 84½ in (215 cm) for an 80 in door. Johnson's frame for a 30 × 80 in door is listed for a 61 × 84½ in opening (Cabinet Parts, Johnson 1500 frame; height from Johnson's frame sheet).

Two pocket doors that meet in the middle need a rough opening four times the door width with Johnson's 1500 frames: 120 in for a pair of 30 in doors (Johnson 1555 converging door kit). Frames for 2×6 walls, such as Johnson's 1560 series, need door height plus 5 in.

Bifold closet door openings

Bifold doors are sized to the finished opening, the hole left after the drywall or trim is on, not to the rough opening. JELD-WEN prints the finished opening on the box: it is ½ in wider than the bifold set, for a ¼ in gap at each side, and 1½ in taller, for the track above and the bracket below. The finished opening should be within ¼ in of the size on the box (JELD-WEN bifold installation instructions).

The width on the label is the finished opening it fits: Reeb, a door distributor, says a 3/0 bifold is for a 36 in opening and a 6/0 for 72 in, with the doors themselves slightly narrower. Reeb lists an 81 in finished opening for its 78 to 79 in tall bifolds, with the hardware adjusting from about 80 to 81½ in for different floors (Reeb).

To get the rough opening, add the wall finish. With ½ in drywall wrapped into the opening, that is 1 in more in width and ½ in more in height: about 37 × 81½ in for a 36 in bifold with a 81 in finished opening. With ¾ in wood jambs, add 1½ in and ¾ in.

Barn doors: no rough opening needed

A barn door hangs on a track in front of the wall, so it covers an existing opening instead of fitting into one. Rustica, a barn door hardware maker, makes the panel 2 in wider than the opening on each side, 40 in for a 36 in opening, and suggests more overlap for bathrooms and bedrooms. A standard track goes at least 6 in above the opening, and for a single panel it is about twice the panel width, so the door can slide clear (Rustica).

Wall thickness and jamb width

The jamb has to match the wall's thickness. A 2×4 stud is 3½ in deep (NIST PS 20), and ½ in drywall on each side makes the wall 4½ in thick. That is why the standard interior jamb is 4 9/16 in, and a 2×6 wall takes a 6 9/16 in jamb (Door and More). Measure the wall at the opening before ordering; plaster, paneling or tile change it.

How to measure a rough opening

1. Width. Measure between the studs at the top, the middle and the bottom. Use the smallest figure.
2. Height. Measure from the subfloor to the underside of the header on both sides. Note how thick the finished floor will be.
3. Square. Measure both diagonals, corner to corner. If they match, the opening is square.
4. Plumb. Hold a level against each side. A side that leans can be shimmed straight, as long as the opening is big enough.
5. Wall thickness. Measure the wall, finish to finish, and order the matching jamb width.
6. Compare. Check your figures against the maker's sheet for the exact door. Interior openings run about 2 in wider and 2 to 2½ in taller than the door; exterior openings about 2½ in each way.

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