Cutting stringers wrong wastes timber and creates a staircase that feels awkward every day.
About this calculator
Cutting stringers wrong wastes timber and creates a staircase that feels awkward every day. The fix is simple math: divide total rise by a comfortable step height, check the run, and verify the Blondel sum before you mark the saw.
Enter total rise in centimetres (finished floor to finished floor), your target riser height (17–19 cm is typical in Indian homes), and tread run (25–30 cm is common). The calculator rounds to a whole number of risers, recalculates the actual rise so steps are equal, counts treads, total horizontal run, and stringer length along the slope.
Building codes vary by city, but 2R + T between 59 and 65 cm is a widely used comfort band. Steep stairs save floor space but tire users; shallow stairs need more run. Landings are required on long flights in many codes — split the rise if one flight exceeds about 16–18 risers. Compare floor area impact with the [[square-footage]] calculator and check headroom against your [[height]] measurements on the floor plan.
Common uses
- Laying out a timber staircase for a duplex or mezzanine
- Checking a carpenter
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Frequently asked questions
Why is the tread count one less than risers?
The top finished floor is the last riser — you do not walk on a tread there. A flight from ground to first floor with 16 risers has 15 treads you step on.
What is the Blondel formula?
2R + T ≈ 59–65 cm, where R is riser height and T is tread run in centimetres. It keeps stairs from feeling too steep or too shallow.
What rise is allowed in homes?
Many residential codes cap risers around 19 cm and require minimum tread depth near 25 cm. Always confirm local NBC or municipal rules before building.
How do I measure total rise?
Measure finished floor to finished floor, including tile or screed thickness on both levels. Use a plumb line or laser — do not measure along an existing raked stringer.
When do I need a landing?
If a single straight flight exceeds about 16–18 risers, split with a landing or winder. Long uninterrupted flights are tiring and often fail inspection.