Standard door sizes

Interior doors

Nominal sizes are quoted width × height, in feet and inches — a "two-six" is 2′-6″ wide, or 30″. Height is 80″ (6′-8″) in the overwhelming majority of American houses.

• Height: 80″ standard. 84″ (7′-0″) and 96″ (8′-0″) show up in newer construction and higher-ceiling rooms — increasingly common on the main floor of a spec house.
• Thickness: 1⅜″ for interior doors, 1¾″ for exterior. That extra ⅜″ is why exterior slabs don't drop into interior frames.

Exterior, patio, and garage

The sliding-patio line is the one that catches people out on delivery day. A 72″ slider sounds generous until you remember the fixed panel never moves: you get roughly 34–35″ of actual opening, no better than a front door.

Nominal, rough, clear — the three numbers

This is the part that causes the arguments.

• Nominal (slab) size — what you order. A 36″ door.
• Rough opening — what the framer leaves. For a prehung door, roughly slab width + 2″ and slab height + 2½″, giving room for the jamb and shims. Our 36 × 80 door wants about a 38 × 82½″ hole.
• Clear opening — what actually passes through, and the only number furniture cares about. With the door standing open at 90°, the slab and its stop eat into the frame: expect roughly 1½–2″ less than nominal. A 36″ door gives about 34″; a 30″ door gives about 28″.

Measure the clear opening yourself — door open, tape from the face of the slab to the opposite stop. Lifting the door off its hinges buys most of that back, and it is the cheapest trick in moving.

Closets and the sizes that aren't doors

What the code asks for

Two numbers get quoted constantly, and they mean different things:

• Egress (IRC R311.2): a dwelling needs at least one side-hinged exterior door giving a minimum 32″ clear width and 78″ clear height. In practice that is why the front door is 36 × 80.
• Accessible routes (ICC A117.1 / ADA 404): 32″ minimum clear width at a doorway. A 32″ slab is borderline once the stop is subtracted, which is why accessible design specifies 36″ doors.

Verify locally. Codes are adopted and amended jurisdiction by jurisdiction, and remodels get treated differently from new construction. Treat the above as the shape of the rule and your building department as the authority.

Do it once, on the plan

Door sizes only matter in relation to something you're trying to move through them. Poché's doorway tool marks every opening on your actual floor plan once — then every piece you place or shop is checked against your real openings, not a generic 36″ assumption. Where the vendor publishes carton dimensions, the verdict is asserted from those; where it's estimating, it says so and tells you to verify.