Nominal, finished and clear are three different widths
A door is sold by the slab width. The framed hole is bigger than that. The finished opening between the jamb faces is a little bigger than the slab, by the hanging gap. And the clear passage, the thing a person or a sofa actually goes through, is smaller than all of them, because the open slab is standing in the opening and the stop is projecting into it from the other side.
| Slab | Jamb to jamb | Clear at 90 degrees | With a swing clear hinge |
|---|---|---|---|
| 24" | 24-1/4" | 22-3/8" | 23-3/4" |
| 28" | 28-1/4" | 26-3/8" | 27-3/4" |
| 30" | 30-1/4" | 28-3/8" | 29-3/4" |
| 32" | 32-1/4" | 30-3/8" | 31-3/4" |
| 36" | 36-1/4" | 34-3/8" | 35-3/4" |
Those figures use a 1-3/8 slab, an eighth of an inch of gap on each side and a half inch stop, which is what the calculator defaults to. Change the stop to 3/8 and every clear figure gains an eighth. The pattern that matters is the constant: with a standard butt hinge you lose roughly the slab thickness plus the stop, less the hanging gaps, so about 1-5/8 inches off the label on a typical interior door.
The angle matters far more than people expect
Everything above assumes ninety degrees. A door that only opens to seventy, because a radiator or a base cabinet corner is in the way, does not lose two ninths of the passage — it loses most of it. The slab width itself is still projecting across the opening at that angle, and thirty two inches of slab laid over at seventy degrees blocks far more of the way than an inch and three eighths of slab edge does at ninety. On the default numbers a 32 inch door held at seventy leaves about 19-1/2 inches.
Run the numbers on a 32 inch door with a half inch stop: about 30-3/8 clear at ninety, roughly 22-1/8 at seventy five, about 14-9/16 at sixty, and around 8-1/8 at forty five. The jump between sixty and ninety is where furniture, appliances and anything on wheels either fits or does not. If something limits how far a door opens, find out what angle it stops at before you assume the width is fine. The door swing planner takes a list of obstructions and returns that angle.
Getting width back without moving the framing
Three things take width away and each has a different remedy. The stop is the cheapest to attack: an applied stop can be relocated or replaced with a thinner one, and on a rabbeted jamb it is part of the jamb and cannot be. The slab thickness is fixed unless the hinge changes. A swing clear hinge, which is a hinge with an offset leaf that carries the slab clear of the opening when it is open, returns the whole slab thickness, and on the numbers above that is between an inch and three eighths and an inch and three quarters back.
The expensive remedy is the opening itself. Going from a 32 to a 36 inch slab means a wider rough opening, which on a bearing wall means a header sized for the new span and a permit almost everywhere. That is a structural job, not a trim job, and the rough opening calculator and header load calculator cover the input side of it. Neither they nor this page size a member or approve an opening.
Where the target number comes from, and where it does not
This calculator will happily compare your opening to any target you type in and tell you how far over or under it is. It has no view on what that target should be. Accessible route clear widths, egress widths, the maneuvering space beside a door, the hardware that has to be operable in a particular way, and how any of it applies to a house against a public building — all of that comes from the code your jurisdiction has adopted, the edition it adopted, and how the local building department reads it. Two towns fifteen miles apart can answer differently.
So the workflow is: ask the building department or the design professional on the project what figure applies to your opening, put that number in the target field, and use the result to decide what to order. Treat any measurement this page produces as a dimension to verify on the finished opening with a tape, not as a determination that anything complies. And for a fire-rated opening, the door, frame, hinges and stop are part of a tested assembly. Nothing about that assembly is yours to modify to gain an inch, and the manufacturer listing is the only authority on it.
Measuring an existing opening
The tape measure version of everything above: open the door as far as it goes, then measure from the face of the open door to the stop on the opposite jamb, at about the height of your waist. That single measurement is the clear passage, and it includes the stop, the slab and the hinge automatically. Do it at the actual angle the door opens to, not with the door pushed hard against whatever is stopping it.
If you get a different number from this calculator, the calculator is the one that is wrong, because it is working from dimensions you typed and the tape is working from the building. Common reasons for a gap between the two: a thicker slab than assumed, a stop set proud, a door that does not reach ninety, or a strike-side gap that is not the eighth of an inch you entered. Related: bifold and bypass doors lose width in a completely different way, and pocket and barn doors mostly do not lose it at all, which is the main reason to use them.
Questions people ask
What is the clear width of a 32 inch door?
With a 1-3/8 slab, an eighth of an inch of hanging gap each side and a half inch stop, a 32 inch door open at ninety degrees gives about 30-3/8 inches of clear passage. Change the stop to 3/8 and it becomes 30-1/2. Fit a swing clear hinge so the slab leaves the opening and it goes to about 31-3/4. Measure your own stop and slab thickness rather than assuming, because those two numbers move the answer by more than an inch between common combinations.
Does the door thickness really come off the clear width?
Yes, on a standard butt hinge. The hinge pivots close to the jamb, so when the door is open at ninety degrees the slab is standing edge-on across the hinge side of the opening and its full thickness is in the way. This is exactly why swing clear hinges exist: the offset leaf carries the slab out past the jamb line when it is open, which returns the slab thickness to the passage. It also changes how the door behaves in the frame, so it is a hardware decision to make with the door manufacturer rather than a swap to make casually.
Is a 32 inch door wide enough for a wheelchair?
That is not something this calculator can answer, and the honest answer depends on which code applies to the building, which edition your jurisdiction adopted, the approach direction, the hardware and what is on both sides of the opening. What the page does is give you the clear passage measurement so you can compare it to whatever figure the building department, the project designer or the accessibility consultant gives you. Get the number from them and put it in the target field. A door that measures fine can still fail on maneuvering clearance beside it, which is a separate requirement about floor space, not width.
How do I measure clear width on a door that is already hung?
Open the door as far as it will actually go, then measure from the face of the open door slab to the face of the stop on the opposite jamb. Take it at roughly waist height where the passage is narrowest in practice. That one dimension automatically includes the slab, the stop and the hinge geometry, which is why it is more reliable than adding up parts. Do not force the door past whatever is stopping it to get a better number, because the number you want is the one you get on an ordinary day.
Can I get more clear width without changing the door size?
Sometimes. Removing or thinning an applied stop returns whatever it was projecting, typically 3/8 to 1/2 inch, though the stop is doing a job and losing it changes how the door closes and seals. A swing clear hinge returns the slab thickness. Taking the slab off entirely and casing the opening returns everything, which is the usual answer for an interior opening that never needed a door. Widening the opening is the only remaining option and it is structural work on a bearing wall. On a fire-rated opening none of these are available, because the stop, hinges and slab are all part of a listed assembly.