About this calculator
Lay out a straight flight: the number of risers, exact riser height, total run, angle and stringer length, checked against Approved Document K for private stairs.
How it’s calculated
Risers = ceil(total rise ÷ maximum riser). Exact riser = total rise ÷ risers. Treads = risers − 1. Run = treads × tread depth. Stringer ≈ √(rise² + (run + one tread)²).
Approved Document K, private stair: rise 220 mm max, going 220 mm min, pitch 42° max, 2R + G between 550 and 700 mm, headroom 2.0 m.
Worked example
With these inputs:
- Total rise (floor to floor)
- 2600 mm
- Maximum riser height
- 220 mm
- Tread depth (going)
- 250 mm
- Nosing overhang
- 20 mm
- Stair width
- 900 mm
the result is:
- Risers
- 12 risers @ 217 mm
- Total run (going)
- 2.75 m
- Stair angle
- 40.9°
- Stringer length (approx.)
- 3.97 m
- 2R + G
- 683 mm
Tips from the trade
- Measure the total rise to the finished floor at both ends, not to the subfloor.
- Treat this as a layout check. Local code and the inspector have the final say.
- For stairs wider than 900 mm, add a middle stringer.
Common questions
How many steps for a 2.6 m rise?
2600 mm ÷ 220 mm = 11.8, so 12 risers at 216.7 mm.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and the Building Regulations before ordering.