Stair Calculator

Calculate rise, run, number of steps, and stringer length with building code awareness.

Stair Dimensions

Unit System

Total Rise (in)

Ideal Step Rise (in)

Ideal Step Run (in)

Step Specifications

Planning a staircase?

Enter the total vertical height from floor to floor to see how many steps you need and the exact dimensions for each.

Overview

Stair calculations ensure that every step is equal in height and depth, which is critical for safety. The total rise is divided by the target step height to find the number of steps, then the actual rise is recalculated for a perfect fit. Correct stringer calculation prevents wasted material and ensures structural integrity.

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Pro Tips

Consistency is key—even a 1/4 inch (6mm) difference between steps can cause someone to trip.
Building codes often specify a maximum rise of 7.75 inches (19.7cm) and a minimum tread depth of 10 inches (25.4cm).
Don't forget to account for the thickness of the tread material when measuring the first and last steps.

Fun Facts

"The worlds longest stairway is the service stairway for the Niesenbahn funicular in Switzerland, with 11,674 steps!"
"Spiral staircases in medieval castles were almost always built winding clockwise (going up) to give the defenders an advantage."
"A common rule of thumb is the "7-11" rule: a 7-inch rise and an 11-inch run."

Formula: Steps = Round(Total Rise / Target Rise); Actual Rise = Total Rise / Steps

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