Stair Rise & Run Calculator
Riser/tread layout for a floor height — with the comfort-formula verdict.
Every riser in a flight must be equal within 5 mm — a single odd step is the classic trip hazard, and the inspector's first measurement. The 2R+T rule is Blondel's, from 1675.
Formula
Stair Rise & Run Calculator is a free stair calculator for surveyors, civil engineers and property buyers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Stair Rise & Run Calculator
Riser/tread layout for a floor height — with the comfort-formula verdict. The calculation implements n = ⌈H/riser⌉; comfort: 2R + T = 600–640 mm (NBC India; IRC R311; Blondel's formula). Every riser in a flight must be equal within 5 mm — a single odd step is the classic trip hazard, and the inspector's first measurement. The 2R+T rule is Blondel's, from 1675.
How to use Stair Rise & Run Calculator
- 1Enter Floor-to-floor height in m.
- 2Enter Target riser in mm (Comfort 150–180 · code max usually 190–200).
- 3Enter Tread (going) in mm.
- 4Read Risers needed, Actual riser, Total run (n−1 treads) instantly — no submit button needed.
- 5Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Stair Rise & Run Calculator?
- ✓Implements the standard formula — n = ⌈H/riser⌉; comfort: 2R + T = 600–640 mm
- ✓Reference cited on-page: NBC India; IRC R311; Blondel's formula
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Built-in engineering verdict flags out-of-range results instantly
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Stair Rise & Run Calculator use?+
It computes n = ⌈H/riser⌉; comfort: 2R + T = 600–640 mm, per NBC India; IRC R311; Blondel's formula. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
Every riser in a flight must be equal within 5 mm — a single odd step is the classic trip hazard, and the inspector's first measurement. The 2R+T rule is Blondel's, from 1675.
Are regional land units exact?+
Conversion factors follow state revenue-department values noted on the tool. Units like bigha and katha vary by region, so always confirm the local factor named in your land records.
Is the Stair Rise & Run Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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