Stair calculator
A typical 2.6 m floor-to-floor height needs 12 steps of 216.7 mm. Under Approved Document K, a private stair in a home can have a rise of up to 220 mm, a going of at least 220 mm and a pitch of no more than 42°.
Meets the Approved Document K limits
- Rise of each step
- 216.7 mm
- Pitch
- 40.9°
- 2 × rise + going
- 683 mm
- Treads
- 11
- Total going (floor space)
- 2,750 mm
- Length along the slope
- 3,785 mm
12 steps of 216.7 mm with 250 mm treads fits the limits for a private stair in a home.
For a straight private stair in a home in England. You also need at least 2 m headroom and handrails 900 to 1000 mm high. Building control has the final say.
Steps for common floor heights
Fewest steps allowed, with a 250 mm going.
| Total rise | Steps | Rise each | Pitch | Floor space |
|---|---|---|---|---|
| 2,400 mm | 11 | 218.2 mm | 41.1° | 2,500 mm |
| 2,500 mm | 12 | 208.3 mm | 39.8° | 2,750 mm |
| 2,600 mm | 12 | 216.7 mm | 40.9° | 2,750 mm |
| 2,700 mm | 13 | 207.7 mm | 39.7° | 3,000 mm |
| 2,800 mm | 13 | 215.4 mm | 40.7° | 3,000 mm |
Approved Document K limits for private stairs
| Measurement | Limit |
|---|---|
| Rise of each step | 150 to 220 mm |
| Going of each step | 220 to 300 mm |
| Twice the rise plus the going | 550 to 700 mm |
| Pitch | 42° at most |
| Headroom | 2 m (less is allowed in some loft conversions) |
All steps in a flight should have the same rise and going.
How we calculate this
We divide the total rise by the 220 mm maximum step height and round up, which gives the fewest steps allowed. Every step is then the same height. A straight stair has one fewer tread than risers, because the top step is the upstairs floor.
We then check the result against Approved Document K, the official guidance for meeting the Building Regulations in England.
Questions people ask
What is the maximum step height for stairs in a house?
220 mm for a private stair, under Approved Document K. The going (tread depth) must be at least 220 mm, and the stair can be no steeper than 42°.
How many steps does a staircase have?
Most UK houses have about 12 to 14 steps between floors, depending on the ceiling height and the thickness of the floor.
What is the 2R + G rule?
Twice the rise plus the going should come to between 550 and 700 mm. It keeps the stride comfortable: steep steps need shallower treads, and low steps need deeper ones.
Do the same rules apply in Scotland, Wales and Northern Ireland?
Wales has its own Approved Document K with similar limits. Scotland and Northern Ireland have their own building standards, so check the rules where you live.
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