Stair Calculator
Stair calculator for planning a staircase. Enter total rise to get the number of steps, riser height, total run and stringer length.
Enter your values and press Calculate.
How to use the Stair calculator
Measure total rise from the top of the lower finished floor to the top of the upper finished floor. The calculator chooses the fewest risers that stay under your maximum riser height, so every step is identical — a key safety and building-code requirement.
Always confirm your local building code before building.
Formula
Risers = ⌈Total rise ÷ max riser⌉, Riser height = Total rise ÷ risers, Treads = risers − 1, Total run = treads × tread depth, Stringer = √(rise² + run²).
Frequently asked questions
What is a comfortable stair rise and run?
A common rule is that two risers plus one tread should equal 24–25 inches, e.g. a 7″ riser with an 11″ tread.
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