Stair Calculator
Work out steps, riser height, run, and stringer length.
Enter the total rise (floor-to-floor height), your desired tread run, and a comfortable target riser height to get the number of steps, the actual riser height, the total horizontal run, and the stringer length to cut.
How it works
Divide the total rise by a comfortable riser height (around 7–7.5 inches) and round to whole steps, then divide the total rise by that step count for the actual riser height. Total run is the tread run times the number of treads, and the stringer length is the diagonal: √(rise² + run²).
Frequently asked questions
How do I calculate stairs?
Divide the total floor-to-floor rise by a comfortable riser height (about 7–7.5 inches) and round to whole steps. A 36-inch rise gives 5 steps at about 7.2 inches each.
What is a comfortable riser height?
Around 7 to 7.75 inches per step is typical and code-friendly in many areas. Keep all risers equal for safety.
How long should a stair stringer be?
It's the diagonal of the total rise and total run: √(rise² + run²). A 36-inch rise with a 40-inch run needs a stringer about 53.8 inches long.
Is this calculator free and private?
Yes. Every CubicCabin calculator runs entirely in your browser, so the numbers you enter are never uploaded or stored. There's no sign-up, no limits, and it keeps working even if you lose connection after the page loads.