Stair Calculator
Enter the total rise (floor-to-floor height) and your target step height to calculate the number of steps, the exact riser height each step will actually have, and the total horizontal run.
How the Stair formula works
Working from total rise to a whole number of even steps:
Number of steps = round(Total rise / Target riser height) Actual riser height = Total rise / Number of steps Total run = (Number of steps − 1) × Tread depth
Step-by-step calculation
- Divide total rise by your target riser height and round to the nearest whole number of steps.
- Divide total rise by that whole number of steps to find the exact, even riser height each step will have.
- Multiply the number of treads (one less than the number of risers) by tread depth to find total horizontal run.
Worked example
A total rise of 108 inches, targeting a 7.5-inch riser: Steps = round(108/7.5) = 14. Actual riser height = 108/14 ≈ 7.71 in. With a 10-inch tread depth, total run = 13 × 10 = 130 inches.
Frequently asked questions
Why does the actual riser height differ from my target?
Every step in a staircase must have the same riser height for safety, so the total rise gets divided evenly across a whole number of steps — this almost never lands exactly on your target height, but building codes typically require the result to be close to it.
What's a comfortable standard riser and tread size?
Most residential building codes target a riser height around 7–7.75 inches and a tread depth around 10–11 inches, though exact limits vary by local code.