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Stair Calculator
Calculate the number of steps, riser height, tread depth, total run and stringer length from the total rise.
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How to use it
- Measure the total rise from finished floor to finished floor.
- Enter the maximum riser height your code allows (7¾ in under the US IRC for homes).
- Enter the tread depth (minimum 10 in under the IRC).
How it works
Risers = total rise ÷ max riser, rounded up; riser height = rise ÷ risers. Treads = risers − 1 (when the top landing is the upper floor). Total run = treads × tread depth. Stringer length ≈ √(rise² + run²). A common comfort check: 2 risers + 1 tread ≈ 24-25 in.
Building codes differ by country and city - confirm with your local building department.
FAQ
How many steps for a 9 ft rise?
108 in ÷ 7.75 = 13.9, so 14 risers of about 7.7 in and 13 treads.
What is the maximum stair riser height?
7¾ in for most US homes under the International Residential Code; commercial codes are stricter.
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