How deep does a stair landing need to be?

The IRC requires landing depth to be at least equal to the width of the stairway it serves, measured in the direction of travel, and never less than 36 inches. For a 36-inch-wide stair, the landing must be at least 36 inches deep.

Do I need a landing at the top and bottom of every stair?

Yes. The code requires a floor or landing at the top and bottom of each stairway, plus a landing at every turn between flights. A flight should never start or end directly at a door swing or a drop.

Can a door swing over a stair landing?

A door can swing over a landing only if the landing still meets its minimum dimensions with the door open. Check the remaining clear depth with the door in its most restrictive position, because the swing arc eats into usable landing space.

How big should a U-shaped (180-degree turn) landing be?

For a 180-degree turn, the landing depth needs to be roughly twice the stair width so both flights land fully on the platform. A 36-inch-wide stair typically needs a landing about 72 inches deep at a U-turn.

What is the minimum stair landing size for a 36-inch stair?

36 inches by 36 inches is the residential minimum: 36 inches wide to match the stair, and 36 inches deep in the direction of travel. Wider stairs need proportionally deeper landings.

Does an exterior stair need a landing at the bottom?

Yes. Even when a flight meets the ground, the code expects a defined, stable landing surface at the bottom. Loose soil, mulch, or a single stepping stone does not qualify.

Does a landing need a handrail or guard?

Guards are required on the open sides of a landing where the drop to the floor below exceeds 30 inches. Handrails must remain continuous along the stair flight itself; the landing is where the handrail run ends and turns.

Landing Size Calculator

What Is the Landing Size Calculator?

Landings are the flat platforms that break up a stairway at its top, its bottom, and every turn between flights. A landing gives people a place to rest on a tall flight, breaks the fall path on a long descent, and creates the level surface that doors, furniture, and turning bodies need at each end of a flight. This calculator sizes landings against the residential code so an undersized platform never becomes a framing failure or an inspection surprise. The International Residential Code, section R311.7.6, sets three basic rules for stair landings: there must be a floor or landing at the top and bottom of every stairway, the landing must be at least as wide as the stairway it serves, and no dimension of the landing measured in the direction of travel can be less than 36 inches. A 36-inch-wide stair therefore needs a landing at least 36 inches deep, and a wider stair needs a proportionally deeper landing. Geometry matters as much as code minimums. On an L-shaped stair, the landing at the 90-degree turn must be deep enough to contain the turn without forcing the walking path into the railing. On a U-shaped or switchback stair, where the flight turns 180 degrees, the landing typically needs a depth close to twice the stair width so both flights land fully on the platform.

How to Use This Calculator

Enter the finished stair width, measured across the treads. The landing depth must equal or exceed this number, with 36 inches as the absolute residential floor.
Measure and enter the planned landing depth, the dimension taken along the direction of travel.
Enter the planned landing width across the direction of travel, which must be at least as wide as the stair.
Tell the calculator where the landing sits: top of the flight, bottom of the flight, or at a turn between flights.
If the landing sits at a turn, enter the turn angle (90 or 180 degrees) so the tool checks turn geometry, not just the code minimum. A 180-degree turn needs roughly twice the stair width in depth.
If a door swings over the landing, enter the door leaf width. The calculator subtracts the swing arc and checks the remaining clear depth against the minimum.

Landing Size Calculator