Staircase Design Calculator
A 3 m floor-to-floor height with risers no taller than 175 mm needs 18 risers of 166.7 mm each.
NBC 2016: 190 mm residential, 150 mm public buildings.
NBC 2016: at least 250 mm residential, 300 mm public buildings.
18
- Actual riser height
- 166.6666667 mm
- Number of treads
- 16
- Longest flight going (plan length)
- 2000 mm
- 2R + T (Blondel)
- 583.3333333 mm
- Comfort check
- below 600 mm: steps feel short; increase the tread
- Pitch
- 33.69006753 °
Step-by-step solution
- Risers = ⌈H / R_max⌉ = ⌈3000 ÷ 175⌉ = 18; R = 3000 ÷ 18 = 166.6666667 mm
- Treads = risers − 1 per flight = 16
Staircase Design Formula
Risers = ⌈H / R_max⌉, 2R + T ≈ 600–640 mm
treads = risers − 1 per flight
Worked Example
A 3 m floor height with risers up to 175 mm and 250 mm treads in a dog-legged stair:
- Risers = ⌈H / R_max⌉ = ⌈3000 ÷ 175⌉ = 18; R = 3000 ÷ 18 = 166.6666667 mm
- Treads = risers − 1 per flight = 16
Number of treads: 16 · Longest flight going (plan length): 2000 mm · 2R + T (Blondel): 583.3333333 mm · Comfort check: below 600 mm: steps feel short; increase the tread · Pitch: 33.69006753 °
GATE tip
A dog-legged stair has one tread fewer than its risers in each flight: the landing replaces a tread.
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Frequently asked questions
What are NBC limits for risers and treads?
NBC 2016 Part 4: residential riser at most 190 mm and tread at least 250 mm; public buildings 150 mm and 300 mm.
Why check 2R + T?
It matches the average stride length; values between about 600 and 640 mm feel natural to climb.
Sources
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures .
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
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APA
Scientific Converters. (2026, October 15). Staircase Design Calculator. Retrieved October 29, 2026, from https://scientificconverters.com/calculators/staircase-design-calculator/
IEEE
Scientific Converters, "Staircase Design Calculator," scientificconverters.com. Accessed: Oct. 29, 2026. [Online]. Available: https://scientificconverters.com/calculators/staircase-design-calculator/