Construction
Stair Calculator
Riser count, tread run, stringer length, and stair angle from total rise.
Inputs
Stair Calculator
Result
Risers × treads
16 risers, 15 treads
- Actual riser height
- 17.5 cm
- Total run
- 405 cm
- Stringer length
- 492.4 cm
- Stair angle
- 34.66°
- Check
- Within comfort ranges
How it's calculated
risers = round(rise / riserHeight); run = (risers − 1) × tread; stringer = √(rise² + run²); angle = atan(rise/run)
Common questions
What's a comfortable riser height?
Most codes and comfort guides put risers between 15 and 20 cm (about 6–8 in). Anything taller feels steep; anything shorter feels shuffly.
Why is there one fewer tread than risers?
The top floor itself counts as the last landing, not a tread. So a flight with 16 risers has only 15 treads between them.
Related calculators
Construction
Roof Pitch Calculator
Convert roof pitch (rise/run) to angle in degrees and slope percent.
Construction
Board Feet Calculator
Compute board feet of lumber for pricing and take-offs.
Construction
Concrete Volume
Volume of concrete needed for a slab, plus 10% waste allowance.
Construction
Paint Calculator
Liters of paint required, allowing for coats and coverage.