Stair Calculator
Calculate the number of steps, riser height, tread depth, stringer length, and comfort checks for your staircase.
Stair Design Results
What is the Stair Calculator?
The Stair Calculator helps you design safe and comfortable stairs by calculating the exact number of steps, riser height, tread depth, and stringer length from your total rise and run measurements.
How to Use
- Measure the total vertical rise from floor to floor in inches.
- Measure or decide the total horizontal run available in inches.
- Enter your desired riser height and tread depth (defaults are common values).
- Click Calculate Stairs to see step counts and comfort checks.
Frequently Asked Questions
What is the ideal riser height?
Most building codes limit riser height to about 7.75 inches. A comfortable riser is typically between 7 and 7.5 inches.
What is the 2R+T rule?
The 2R+T rule (twice the riser height plus the tread depth) should equal approximately 24 to 25 inches for comfortable stairs. Values outside this range may feel too steep or too shallow.
How do I calculate stringer length?
The stringer length is the hypotenuse of a right triangle formed by one step's rise and run, multiplied by the total number of steps.
What is headroom and why does it matter?
Headroom is the vertical clearance above the stairs. Most codes require at least 6 feet 8 inches. Low headroom can be dangerous and uncomfortable.