Door Size Calculator
Enter the door's width and height, the door type and the wall thickness. The calculator gives the rough opening to frame, the clear opening when the door is open and whether it is wide enough for a wheelchair.
- Rough opening
- Clear width
- Wheelchair check
Door sizes are written width by height. Wall thickness is the finished wall, including both linings.
The hole in the wall is bigger than the door. A prehung interior door needs a rough opening about 2 inches wider and 2.5 inches taller than the door, for the frame and room to level it. A 32 × 80 inch door needs a 34 × 82.5 inch opening.
Door rough opening chart
Prehung interior doors. Search for a door.
| Door (in) | Rough opening (in) | Clear opening (in) |
|---|---|---|
| 24 × 80 | 26 × 82.5 | 22.25 |
| 28 × 80 | 30 × 82.5 | 26.25 |
| 30 × 80 | 32 × 82.5 | 28.25 |
| 32 × 80 | 34 × 82.5 | 30.25 |
| 34 × 80 | 36 × 82.5 | 32.25 |
| 36 × 80 | 38 × 82.5 | 34.25 |
Exterior doors need about half an inch more each way.
Door width and opening
80 inch interior door. Slide the door width.
The frame is drawn round the door, with the rough opening marked above.
How to frame a door opening
Door plus allowance. Step through it.
Door size
Width and height.
Use a level to check the floor across the opening before you set the frame height.
Prehung, slab or pocket door
Door types. Compare them.
Door hung in its frame.
Door only.
Slides into the wall.
Pocket doors slide into the wall and need a rough opening about twice the door width.
Before framing
Door checks. Tick each item.
Tick each item as you go.
Allow for the finished floor. A thick tile floor still to go in needs a taller opening.
What you get
Door opening. Each tile explains one result.
To frame.
When open.
Wheelchair width.
Wall thickness.
Span.
Wheelchair users need at least 32 inches clear, so choose a 36 inch door where you can.
Frequently Asked Questions
No question matches that search.
What is a rough opening for a door?
The framed hole in the wall that the door and its frame fit into.
How much bigger is a rough opening than the door?
About 2 inches wider and 2.5 inches taller for a prehung interior door.
What is the standard interior door size?
In the US, 80 inches tall and 24 to 36 inches wide. In the UK, 1981 × 762 mm is common.
What door width do I need for a wheelchair?
At least 32 inches clear, which usually means a 36 inch door.
What is the clear opening of a door?
The space you can walk through when the door is open, about 1.75 inches less than the door width.
How wide should a door jamb be?
The same as the finished wall thickness, about 4 9/16 inches for a 2 × 4 stud wall.
Do exterior doors need a bigger opening?
Yes, a little, for the threshold and thicker frame.
A door that fits the hole
Add the right allowance to the door size, frame the opening square and check the clear width. The door will hang straight and close sweetly.
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