Door Clearance Calculator
Enter the door leaf width and its frame, and the door clearance calculator gives the floor the door sweeps, the clear opening it leaves when open at 90°, and how far it opens before it meets a wardrobe, bed or wall you place in its path.
Door clearance calculator
Planning aid, not a building-code check. Requirements vary by jurisdiction and building type. Confirm with your local rules or a qualified professional. Accessible door widths and manoeuvring spaces are set by local rules and are not checked.
Bare numbers are meters; 190 mm works too.
Leave blank (or 0) to use the leaf plus a gap each side.
Leave blank (or 0) when nothing is in the way.
Assumptions
Change any value to match your product or local rules.
Basis: Example. Measure your door and frame
Basis: Example. Measure your door and frame
Basis: Example. Measure your door and frame
Basis: Example 3 mm each side; doors and frames vary
- Swing radius
- 0.90 m
- 2′ 11″
- Swing area
- 0.64 m²
- 6.8 sq ft
- Clear opening (door at 90°)
- 858 mm (33.78 in)
- How far it opens
- 41.8°, then it meets the obstacle
- Floor depth the swing needs
- 0.90 m
- 2′ 11″
A 0.90 m (2′ 11″) leaf sweeps 0.64 m² (6.8 sq ft) of floor and stops at 41.8° against an obstacle 0.60 m (2′) from the wall.
How this was calculated
- Swing radius = leaf width; swing area = π × W² ÷ 4 at 90° (÷ 2 at 180°)
- Clear opening at 90° = jamb-to-jamb − leaf thickness − stop − hinge offset
- An obstacle d from the wall stops the leaf at asin(d ÷ W) when d is less than W
- Swing area = π × (0.90 m)² ÷ 4 = 0.64 m²
- Clear opening = 910 mm (35.83 in) − 40 mm (1.57 in) − 12 mm (0.47 in) − 0 mm (0.00 in) = 858 mm (33.78 in)
- Opening angle = asin(0.60 m ÷ 0.90 m) = asin(0.667) = 41.8°
How it works
Swing radius
The leaf turns about its hinges, so the free edge traces a quarter circle with a radius equal to the leaf width.
Swing area
π × W² ÷ 4 for a 90° swing, π × W² ÷ 2 if the door folds back to 180°.
Clear opening
Jamb-to-jamb width minus the open leaf’s thickness, the door stop on the latch side and any hinge-side offset.
Obstacles
At angle θ the leaf’s free edge is W × sin θ from the wall, so an obstacle d away stops it at asin(d ÷ W).
Worked example
A 900 mm leaf in a 910 mm opening, 40 mm thick with a 12 mm stop, leaves 910 − 40 − 12 = 858 mm (about 33.8 in) clear when open at 90°. It sweeps π × 0.9² ÷ 4 ≈ 0.636 m² of floor. A wardrobe 600 mm from the door’s wall stops it at asin(600 ÷ 900) ≈ 41.8°.
In imperial, a 36 in leaf in a 36 in opening, 1¾ in thick with a ½ in stop, leaves 33¾ in clear, sweeps about 7.07 sq ft and also stops at 41.8° against an obstacle 24 in away.
Door width vs clear opening
A door sold as 900 mm or 36 in is the width of the leaf. The space you can walk or carry furniture through is smaller: the open leaf still stands in the opening on the hinge side, and the stop narrows the latch side. Where rules set a door width, check whether they mean the leaf or the clear opening; check furniture against the clear opening.
Measure your frame between the jambs and the leaf thickness, and replace the example values. Hinges that throw the leaf clear of the opening reduce the loss; enter 0 for the hinge offset in that case.
Swing space and where furniture can go
The swing needs a clear quarter circle of floor with a radius of the leaf width, plus room behind the open leaf if it is to fold back flat. Anything taller than a skirting board inside that quarter circle stops the door short.
Put the obstacle distance in to see how far the door would open with a bed, wardrobe or radiator in the way. A door that opens to 40° or so makes the room hard to enter with anything bulky.
Doors that open into corridors or each other
A door opening into a corridor takes up to its leaf width of the corridor while it is open. Two doors close together on adjacent walls can hit each other; draw both swings and see whether the arcs overlap. The corridor width calculator helps with the first case; for the second, sketch the doors in the floor plan editor and look at the arcs.
Sliding and pocket doors
Sliding and pocket doors have no swing, so the swing results do not apply. Their clear opening is the opening minus whatever part of the leaf stays in it when fully open; measure that overlap and subtract it yourself.
Frequently asked questions
What is door swing clearance?
The floor area a hinged door needs to open: a quarter circle with a radius equal to the leaf width for a 90° swing, or a half circle if it folds back to 180°. Keep it free of anything taller than the skirting.
How is clear opening width measured?
With the door open at 90°, from the face of the open leaf to the door stop on the opposite jamb. It is the jamb-to-jamb width minus the leaf thickness, the stop and any hinge-side offset.
How much space does a door need to open?
A depth equal to the leaf width in front of the wall, along the full leaf width. A 900 mm door needs 900 mm of clear floor on its swing side; a 36 in door needs 36 in.
Can furniture go behind a door?
Only if it is shallow enough to sit between the open leaf and the wall, or if you accept that the door will not open fully. Enter the furniture’s distance from the door’s wall to see the angle the door stops at.
Which way should a door swing?
It is a trade-off: swinging into the room keeps corridors clear, swinging against the nearest wall keeps the room usable, and swinging out of small rooms such as bathrooms makes it easier to reach someone who has fallen against the door. Your local rules may also decide for some doors.
Ready to plan your space?
It is free, runs in your browser and needs no account. Projects are saved privately on this device.