How to use the door size guide
A door's nominal size is the size of the leaf, but codes care about the clear opening: the space a person or wheelchair can actually pass through once the door is open. This guide turns a leaf size into an estimated clear width and height, checks it against the minimum you pick, and suggests the smallest standard door that would pass.
- Pick the units and the requirement. Choose the IRC egress door for the main exit of a house, the IBC/ADA option for doors on an accessible route in public and commercial buildings, or no minimum for ordinary interior doors.
- Enter the leaf width and height. For a pair of doors, enter the width of one leaf; the check applies to the active leaf, as IBC 1010.1.1 and ADA 404.2.2 require.
- Enter the leaf thickness and stop overlap. Interior leaves are usually 1⅜ in (35 mm) and exterior leaves 1¾ in (44 mm). The leaf usually tucks about ½ in (12 mm) behind the stop.
- Read the results: estimated clear width and height, pass or fail, the minimum leaf width for the chosen rule, the framed rough opening and the nearest standard size.
Door clear width formula
Clear width ≈ leaf width − leaf thickness − stop overlap
Clear height ≈ leaf height − stop overlap
Minimum leaf width ≈ required clear width + leaf thickness + stop overlap
Rough opening ≈ leaf width + 2 in (51 mm) × leaf height + 2½ in (64 mm)
The codes measure clear width between the face of the door and the stop with the door open 90 degrees. With ordinary butt hinges the open leaf sits in the opening, so its thickness is lost on the hinge side and the stop is lost on the latch side. These are estimates; swing-clear hinges, lever handles and thick frames change the figure, so measure a real sample for tight cases.
Code minimums for door size
| Rule | Clear width | Clear height |
|---|---|---|
| IRC R311.2 egress door (one per dwelling unit, side-hinged) | 32 in (813 mm) | 78 in (1,981 mm) |
| IBC 1010.1.1 means of egress doors | 32 in (813 mm); leaf 48 in nominal max | 80 in (2,032 mm); 78 in inside dwelling units |
| ADA 404.2.3 accessible doors | 32 in (815 mm) | No height in 404.2.3; IBC still applies |
| ADA 404.2.3 openings more than 24 in deep | 36 in (915 mm) | - |
ADA 404.2.3 also bans projections into the clear width below 34 in above the floor and limits them to 4 in between 34 and 80 in. Thresholds are limited to ½ in (404.2.5), and hardware must sit 34–48 in above the floor (404.2.7).
Standard door sizes
| Market | Common leaf widths | Common heights | Thickness |
|---|---|---|---|
| US interior | 24, 28, 30, 32, 36 in | 80 in (6′8″), 96 in (8′) | 1⅜ in |
| US exterior | 32, 36 in (42 in for wide entries) | 80, 84, 96 in | 1¾ in |
| US commercial | 36 in (pairs 2 × 36 in) | 84 in (7′0″) | 1¾ in |
| UK imperial range | 610, 686, 762, 838 mm | 1,981 mm (6′6″) | 35 mm internal, 44 mm external |
| UK metric range | 626, 726, 826, 926 mm | 2,040 mm | 35 mm internal, 44 mm external |
Worked examples
Front door of a house
A 36 × 80 in exterior door, 1¾ in thick: clear width ≈ 36 − 1.75 − 0.5 = 33.75 in and clear height ≈ 79.5 in. Both beat the IRC R311.2 minimums of 32 in and 78 in, so it works as the required egress door.
Is a 32 in bedroom door accessible?
A 32 in interior leaf, 1⅜ in thick: clear width ≈ 32 − 1.375 − 0.5 = 30.1 in, which is short of the 32 in clear that ADA 404.2.3 asks for. A 34 in leaf gives about 32.1 in, and a 36 in leaf about 34.1 in, so specify 36 in where an accessible route matters.
Commercial door height
An 80 in tall leaf gives about 79.5 in clear, under the IBC's 80 in minimum. That is why commercial door schedules use 84 in (7 ft) leaves, which give about 83.5 in.
Who this guide can help
- Architects and interior designers writing door schedules and checking accessible routes before drawings go to plan review.
- Builders and remodelers ordering prehung doors and framing rough openings that match.
- Accessibility consultants and aging-in-place planners checking whether existing doors give 32 in clear or need widening.
- Homeowners replacing doors or planning a renovation who want to know which size to buy.
- Students learning the difference between nominal leaf size and clear opening.
Practical tips
- Swing-clear (offset) hinges move the open leaf out of the opening and can win back roughly the leaf thickness, about 1½ in, of clear width without reframing.
- Leave space beside the latch for maneuvering clearance on accessible doors; ADA 404.2.4 sets this by approach direction, and the bathroom clearance guide and furniture clearance guide help with the room around the door.
- Frame openings with the rough opening calculator, check bedroom windows with the egress window calculator, and plan step-free entries with the ramp slope calculator.
- Pocket and barn doors lose less width to the leaf but often more to the pull; measure the real clear opening with the door fully open.
Want to see new doors or a widened opening in your room? Try a few looks on a photo with AI Room Redesign.
