Stair Size Calculator
Enter the total rise from finished floor to finished floor and choose a set of rules. The calculator works out how many steps you need, the height of each riser, the depth of each going, the total run and the pitch.
- Equal risers
- UK and US rules
- Pitch check
Measure the rise with floor finishes in place, or allow for them. Rules shown are simplified; check your local code.
A good stair has every step the same, at a comfortable stride. People notice even a few millimetres' difference between steps, and trip. The rise is divided into equal risers, and each going is set so that two risers plus one going falls close to a natural stride of about 630 mm.
Stair dimension chart
UK private stairs. Search for a floor height.
| Total rise (mm) | Risers | Rise (mm) | Going (mm) | Total run (mm) | Pitch |
|---|---|---|---|---|---|
| 2400 | 12 | 200 | 230 | 2530 | 41.0° |
| 2500 | 13 | 192 | 245 | 2945 | 38.1° |
| 2600 | 13 | 200 | 230 | 2760 | 41.0° |
| 2700 | 14 | 193 | 244 | 3176 | 38.3° |
| 2800 | 14 | 200 | 230 | 2990 | 41.0° |
| 3000 | 15 | 200 | 230 | 3220 | 41.0° |
US stairs need deeper treads, so they run longer for the same height. A comfortable stair runs longer still.
Total rise and steps
UK private stair. Slide the total rise.
The drawing shows the flight from the side. Each step adds one riser and, except the top, one going.
How to work out a stair
Rise, then going. Step through it.
Measure the rise
Finished floor to finished floor.
There is always one fewer tread than risers, because the top step is the landing or upper floor.
UK, US or comfort rules
Different limits. Compare them.
Compact stairs for homes.
IRC rules with deeper treads.
Easy for children and older people.
Public buildings have stricter rules again, typically 170 mm rise and 250 mm going.
Stair checks
Safety and comfort. Tick each item.
Tick each item as you go.
Handrails are needed on at least one side, both sides if the stair is wider than 1 m.
What you get
Stair geometry. Each tile explains one result.
Number of risers.
Each step height.
Tread depth.
Total length.
Angle of the stair.
2R + G between 550 and 700 mm is the UK comfort range. Aim near the middle.
Frequently Asked Questions
No question matches that search.
How many steps for a 2.6 m floor height?
13 risers of 200 mm under UK rules, with 12 treads.
What is the maximum riser height?
220 mm for UK private stairs, 7¾ in (196 mm) in the US.
What is the 2R + G rule?
Two risers plus one going should be about 550 to 700 mm, ideally near 630.
How long is a staircase?
About 2.5 to 3.5 m of run for a typical house.
What is the maximum stair pitch?
42° for UK private stairs.
Do all steps have to be the same height?
Yes. Uneven steps cause trips.
How much headroom does a stair need?
2 m in the UK, 6 ft 8 in in the US.
Steps that feel right
Divide the rise into equal steps, set a comfortable going and check the pitch. The stair will meet the rules and feel natural to climb.
More size calculators
Each one has its own calculator, worked examples and answers to common questions.