Stair dimensions: riser, going and headroom
A staircase is the one part of a house plan you cannot draw by eye. It is worked out from the height it has to climb, and every step has to be identical — because people climb stairs by rhythm, and the odd step is the one that trips them.
The two dimensions everything follows from
- The riser is the vertical height of one step.
- The going (or tread) is the horizontal depth you put your foot on.
Note the counting: a flight has one more riser than it has treads, because the last riser lands you on the floor above rather than on another tread. Getting this wrong by one is the classic stair mistake, and it puts the top step out by a full riser.
What is comfortable
| Comfortable | Workable range | |
|---|---|---|
| Riser | 6 3/4" | 6" – 7 1/2" |
| Going | 10" – 11" | 9" – 12" |
| Width of flight | 3'-6" | 3'-0" minimum |
| Headroom | 7'-0" | 6'-8" minimum |
| Landing depth | the width of the flight | 3'-0" minimum |
The relationship between the two is what makes a stair feel right. The old rule is that twice the riser plus the going should land between 24 and 25 inches. A 6 3/4" riser wants about a 10 1/2" going; a steeper 7 1/2" riser wants a shallower 9 1/2".
A worked example: 9 ft floor to floor
Measure from finished floor to finished floor — not to the ceiling, which leaves out the thickness of the floor structure above. Say that comes to 9'-0", which is 108 inches.
- Divide by a comfortable riser: 108 ÷ 7 = 15.4. That is not a whole number, and a stair cannot have four tenths of a step.
- Round it: 16 risers.
- Work the real riser back out: 108 ÷ 16 = 6.75 inches. Comfortable.
- Pick the going from the rule: 2 × 6.75 = 13.5, so the going should be about 24.5 − 13.5 = 11 inches.
- Sixteen risers means fifteen treads, so the stair needs 15 × 11 = 165 inches, or 13'-9" of floor length.
That last figure is the one that surprises people. A straight flight for an ordinary storey height eats nearly fourteen feet of plan. If the house has not got fourteen feet to spare, the stair has to turn.
Turning the stair
A stair turns at a landing, and the landing is a step in its own right — you arrive on it, you turn, you carry on.
- A quarter turn takes 90° at a landing and costs roughly the width of the flight in each direction. It is the usual way to fit a stair into a corner.
- A half turn, or switchback, doubles back beside itself. It fits the same climb into about half the length, which is why it is what most stairwells use, and the two flights stack over each other.
- A landing with a walkway turns, runs along a corridor for a distance, and then climbs again — useful when the upper floor is reached from somewhere the lower flight does not point at.
- Winders — tapered treads that turn without a landing — save space but are harder to climb and are restricted in many building regulations. Prefer a landing where you can.
Whatever the shape, the riser stays the same the whole way up. Work it out from the total rise over the total number of risers, not flight by flight.
Headroom is the one that gets missed. Measure vertically from the nose of each step to whatever is above it. On a switchback that is the underside of the flight coming back over the top, and if the stair is short the two can close to well under 6'-8" without looking wrong on the plan. It is a mistake you only find when someone hits their head.
Drawing it
On a plan a stair is drawn as its treads with a walking line running up the middle, an arrow pointing up, and a label giving the number of risers — UP 16R. Where a floor cuts through it, the flight is broken with a cut line so it is clear which part belongs to which storey. The landing levels are worth noting too, so a builder knows how high each one sits.
DrawHousePlan works the stair out for you. Give it the foot and the head of the first flight and the floor-to-floor height, and the riser follows from the total rise so every step matches. Add as many landings as you need — quarter turns, switchbacks, any angle, or a landing you walk along before climbing again — and it stays one stair, with one walking line and one UP nR label, drawn in plan and built in 3D.
Check your local rules
The figures here are what is comfortable and commonly built, and they will get a stair drawn sensibly. They are not a substitute for the building regulations that apply where you are: maximum riser, minimum going, minimum width, headroom and handrail heights are all set locally and they differ between countries. Check the rule that governs your project before you build from a drawing.