Door Clearance Calculator
Door clear opening and code pass check.
What it does
Clear opening decides whether a doorway works. Hinges and stops steal about 2 inches from the leaf, so a 36 inch slab yields about 34 inches of passage. Codes draw the line at 32 inches clear, or 815 millimeters.
The tool above subtracts the allowance and grades the result. Defaults of 36 inches give 34 inches clear with Passes 32 in. The metric mirror at 900 millimeters gives 850 millimeters with Passes 815 mm. A 32 inch leaf gives only 30 inches and fails, which surprises owners who shopped by slab size.
Hardware and swing shift real access beyond leaf math. Offset hinges recover a little, thick stops take more, and approach space decides wheelchair use regardless of width. Minimum leaf guidance of 34 inches (865 millimeters) plans the opening before framing.
This page checks leaf arithmetic only. It does not certify compliance, which needs hardware, maneuvering space, and local adoption of the standards. Confirm with the authority before building.
How to use
- Pick imperial (in) or metric (mm).
- Enter the door leaf width.
- Read clear opening first.
- Read pass or fail against 32 in (815 mm).
- Read the minimum leaf for planning.
- Verify swing and hardware on site.
Formula
- leaf_in
- Door leaf width in inches.
- leaf_mm
- Door leaf width in millimeters.
- min
- 32 in or 815 mm minimum clear opening.
Leaf math with a fixed hinge plus stop allowance. At narrow leaves the allowance dominates, so small gains need hardware or reframing. Hardware thickness varies by set.
Worked example
Example: 36 in door leaf
Defaults: imperial 36 in leaf. Metric mirror is 900 mm. Hinge plus stop near 2 in (50 mm).
- Inputs (imperial default): 36 in leaf.
- Clear: 36 minus 2 is 34 in clear.
- Check: 34 meets 32, so Passes 32 in.
- Minimum leaf: 32 plus 2 is 34 in leaf min.
- Metric mirror (900 mm) gives 850 mm clear with Passes 815 mm. Tool shows the same.
Reference table
| Leaf | Clear | Call |
|---|---|---|
| 36 in leaf | 34 in clear | Passes 32 in |
| 32 in leaf | 30 in clear | Fails 32 in |
| 900 mm leaf | 850 mm clear | Passes 815 mm |
| 850 mm leaf | 800 mm clear | Fails 815 mm |
| 34 in leaf | 32 in clear | Passes 32 in |
Limits
- Leaf math only. Swing and hardware excluded.
- Fixed allowance. Sets vary.
- No maneuvering space check.
- Not a compliance certificate.
Common mistakes
- Shopping slab size as clear size.
- Forgetting stop thickness on both sides.
- Assuming pass equals full compliance.
- Ignoring approach space at the latch.
- Measuring the frame instead of the leaf.
Try it yourself
Quick checks. Answers sit tucked under each question.
32 in leaf?
Clear is 30 in. Fails 32 in. Minimum leaf is 34 in.
850 mm leaf?
Clear is 800 mm. Fails 815 mm. Minimum leaf is 865 mm.
Questions
How is clear width figured?
Leaf minus about 2 in for hinge and stop. Here 34 in clear.
What is the minimum clear?
At least 32 in clear (815 mm). Here Passes 32 in.
What leaf meets code?
About 34 in leaf (865 mm), giving 32 in (815 mm) clear.
Does pass mean compliant?
No. Swing, hardware, and approach alter real access. This checks leaf math only.
How do double doors work?
Yes. Pairs need each leaf or the active leaf checked separately.
How do I fix a fail?
Widen the leaf or use offset hinges for a small gain before reframing.