REFERENCE TABLE #99 · CONSTRUCTION · HOME
The most common US door is 36 × 80 inches, and its rough opening — the framed hole it fits into — is 38 × 82.5 inches, covering 20.00 square feet. The rule of thumb on this page is simple: rough opening width = door width + 2 inches, rough opening height = door height + 2.5 inches. Pick any standard size below and the calculator applies that rule, or read the full chart for interior, closet, exterior, double, French, and sliding patio doors.
Rough opening width is the door width plus 2 inches; rough opening height is the door height plus 2.5 inches. The extra room lets you plumb, level, and shim the frame square before the trim goes on. Door area is width times height divided by 144, in square feet. These are planning figures for standard pre-hung doors — always check the manufacturer's own rough-opening spec before you frame.
Every rough opening below follows the same rule: width + 2 inches, height + 2.5 inches. All heights here are the standard 80 inches.
| Door type | Door size (in) | Rough opening (in) | Door area (sq ft) |
|---|---|---|---|
| Interior passage | 24 × 80 | 26 × 82.5 | 13.33 |
| Interior passage | 28 × 80 | 30 × 82.5 | 15.56 |
| Interior passage | 30 × 80 | 32 × 82.5 | 16.67 |
| Interior passage | 32 × 80 | 34 × 82.5 | 17.78 |
| Interior passage | 36 × 80 | 38 × 82.5 | 20.00 |
| Closet bifold | 24 × 80 | 26 × 82.5 | 13.33 |
| Closet bifold | 30 × 80 | 32 × 82.5 | 16.67 |
| Closet bifold | 36 × 80 | 38 × 82.5 | 20.00 |
| Exterior entry | 32 × 80 | 34 × 82.5 | 17.78 |
| Exterior entry | 36 × 80 | 38 × 82.5 | 20.00 |
| Double entry | 60 × 80 | 62 × 82.5 | 33.33 |
| Double entry | 64 × 80 | 66 × 82.5 | 35.56 |
| Double entry | 72 × 80 | 74 × 82.5 | 40.00 |
| French | 60 × 80 | 62 × 82.5 | 33.33 |
| Sliding patio | 60 × 80 | 62 × 82.5 | 33.33 |
| Sliding patio | 72 × 80 | 74 × 82.5 | 40.00 |
Default: a 36 × 80 inch door. Rough opening width: 36 + 2 = 38 inches. Rough opening height: 80 + 2.5 = 82.5 inches. Door area: 36 × 80 ÷ 144 = 20.00 square feet.
Rough opening width: 30 + 2 = 32 inches. Height: 80 + 2.5 = 82.5 inches. Area: 30 × 80 ÷ 144 = 16.67 square feet. This is the classic bedroom-door size in older homes.
Rough opening width: 60 + 2 = 62 inches. Height: 80 + 2.5 = 82.5 inches. Area: 60 × 80 ÷ 144 = 33.33 square feet. For a double door, that 62-inch opening holds two 30-inch slabs plus the frame and the gap between them.
Interior doors are typically 1-3/8 inches thick; exterior doors are typically 1-3/4 inches thick, because they carry weatherstripping, a threshold, and heavier hardware. A pre-hung door arrives already mounted in its frame, so the rough opening on this page is what you frame for it; a slab is just the door leaf, and it must match an existing frame, so measure the frame rather than trusting the chart. Finally, the door size is not the clear opening: hinges, stops, and the door itself eat about 2 inches, so a 36-inch door is the usual route to a 32-inch clear opening — the width a wheelchair or a wide piece of furniture actually passes through.
| Output | Formula | What it means |
|---|---|---|
| Rough opening width | door width + 2 in | 38 in for a 36-inch door — the framed hole width to build. |
| Rough opening height | door height + 2.5 in | 82.5 in for an 80-inch door — room for the frame, shims, and flooring. |
| Door area | width × height ÷ 144 | 20.00 sq ft for 36 × 80 — useful for paint, material, and cost estimates. |
The +2 / +2.5 inch rule is a widely used planning rule of thumb for standard pre-hung doors, not a substitute for the manufacturer's rough-opening specification, which can differ by brand, jamb depth, and threshold type — exterior and sliding patio units vary most. Older homes often have non-standard openings that were trimmed to fit, and flooring thickness changes the effective height: measure the actual opening and the finished floor before ordering. Door area is the slab area only; it excludes the frame, trim, and glass. Error policy: an unrecognized or non-positive size is reported as an error rather than estimated.
Bright Side Kit. "Standard Door Sizes Chart and Rough Opening Calculator." https://brightoolbox.com/door-sizes-chart/ Accessed October 24, 2026.Data sources38 × 82.5 inches for a standard 36 × 80 inch door, by the rule of thumb: width + 2 inches, height + 2.5 inches. Always confirm against the manufacturer's spec before framing.
30 × 80 inches for bedrooms in many homes, with 36 × 80 inches increasingly standard for main rooms and accessible routes. Older homes often have 28-inch doors, which feel narrow for furniture.
36 × 80 inches for a single entry door, with 32 × 80 inches also common. Double entries run 60, 64, or 72 inches wide, all 80 inches tall.
Interior doors are typically 1-3/8 inches thick; exterior doors are typically 1-3/4 inches thick. The extra exterior thickness carries weatherstripping, a threshold, and heavier locks and hinges.
A pre-hung door comes mounted in its frame; a slab is just the door leaf. Frame a new opening to the rough opening for a pre-hung unit. For a slab, measure the existing frame — the chart alone will not guarantee a fit.
Usually a 36-inch door, which gives about a 32-inch clear opening after hinges and stops. A 32-inch door gives only about a 30-inch clear opening, which is tight for many wheelchairs.
Because the frame, shims, and leveling need room. The extra 2 inches of width and 2.5 inches of height let the installer plumb and square the frame in an imperfect framed hole, then cover the gaps with trim.
Most standard US stock doors are 80 inches (6 feet 8 inches) tall. Taller 96-inch doors exist for modern homes with higher ceilings, but they are usually special order and their rough openings follow the same +2.5 inch height rule.