Staircase Calculator: Number of Steps, Riser and Tread
Enter floor-to-floor height, the highest riser you want and the tread depth. You get the number of risers, exact riser height, treads, the horizontal run and the stair angle.
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Number of risers (steps)
18
Within NBC limits- Each riser
- 167 mm
- Treads
- 17
- Total going (horizontal run)
- 4.25 m
- Stair angle
- 33.7 °
Estimate only, based on standard thumb rules. Confirm quantities with your engineer or contractor before you buy.
2R + T = 583 mm, within the comfortable 550–700 mm range.
Show working
- 3,000 ÷ 175 = 17.14 → 18
- R = 3,000 ÷ 18 = 166.7 mm
- 17 × 250 = 4,250 mm
- 2R + T = 583 mm
- θ = atan(166.7 ÷ 250) = 33.7°
How to use
- Enter the floor-to-floor height.
- Enter the maximum riser and the tread depth you want.
- Choose one straight flight or two flights with a landing.
Good to know
Risers = floor height ÷ maximum riser, rounded up; then the real riser = floor height ÷ risers, so every step is equal. A straight flight has one tread fewer than risers; a dog-legged stair with a mid landing has two fewer.
The National Building Code of India 2016 (Part 4) allows residential stairs a riser of up to 190 mm and a tread of at least 250 mm; other buildings need lower risers and deeper treads. Many designers aim for about 150–175 mm risers and 250–300 mm treads.
Comfort check: 2 × riser + tread (Blondel rule) between about 550 and 700 mm feels natural. Leave enough headroom (at least about 2.1 m) above every step and confirm the design with your architect and local bylaws.
Questions
How many steps for a 10 ft floor height?
10 ft = 3048 mm. With a 175 mm maximum riser that is 17.4, so 18 risers of 169 mm each, and 17 treads in a straight flight.
What riser and tread does NBC allow for homes?
NBC 2016 Part 4 allows residential risers up to 190 mm and treads of at least 250 mm.
What is the going?
The total horizontal length of the treads, which tells you how much floor the stair needs (landings extra).
What angle is comfortable?
About 30–37°. Steeper than 40° feels like a ladder.
Does it include landing size?
No. A landing should be at least as wide as the stair; add its length to the going.