Stair Calculator
Design a staircase from the total rise: the calculator splits your floor-to-floor height into equal risers targeting the comfortable 17–18 cm range, then derives the number of steps, total run, stringer length (Pythagoras), stair angle and a Blondel 2R+T comfort check with a per-step layout table.
TheCalculators — Stair Calculator
Printed thecalculators.com
Number of Steps (risers)
16
Riser 17.5 cm · 15 treads · stringer 504.8 cm
Staircase geometry
- Total Rise
- 280 cm
- Risers / Steps
- 16
- Riser Height
- 17.5 cm
- Treads
- 15 @ 28 cm
- Total Run
- 420 cm (165.4 in)
- Stringer Length
- 504.8 cm
- Stair Angle
- 32°
- Blondel 2R + T
- 63 cm (comfortable ✓)
How the staircase was designed
- 11. Divide rise by target riser280 ÷ 17.5 = 16 → rounded to 16 risers
- 22. True riser height280 ÷ 16 = 17.5 cm (code max 19.7 cm)
- 33. Treads and run16 risers → 15 treads × 28 cm = 420 cm total run
- 44. Stringer (Pythagoras)√(280² + 420²) = 504.8 cm, angle 32°
Step-by-step layout
Common code checks: riser ≤ 19.7 cm (7¾ in), tread ≥ 25.4 cm (10 in), headroom ≥ 203 cm (6 ft 8 in), width ≥ 91.4 cm (36 in). Always confirm local building codes before construction.
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Formula
risers = ⌈rise ÷ target riser⌉ · riser = rise ÷ risers · stringer = √(rise² + run²) · comfort: 2R + T ≈ 63 cm
Pro tips
- • All risers must be equal — the top and bottom steps included.
- • Blondel rule: 2 × riser + tread should land between 60 and 66 cm for a natural stride.
FAQ
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