Stair Calculator
Based on the US IRC residential code maximum riser (7¾") and minimum tread depth (10"). Local codes can vary — always confirm with your local building department before building.
Free stair calculator — enter the total floor-to-floor rise and get the number of steps, riser height, total run, and stair angle, with a check against typical US residential building code.
How it works
- Enter the total rise (floor-to-floor height) in inches
- Enter your desired tread depth (default 10 inches)
- See the number of steps, riser height, total run, and stair angle — with a code-compliance check
Frequently asked questions
Why isn't the riser height exactly what I'd expect?
The number of steps is rounded up first, then the total rise is divided evenly across that many steps — every riser needs to be the same height, since uneven steps are a common cause of trips and falls. This calculator finds the step count that keeps risers as close to the ideal 7.5" as possible while staying uniform.
What code does this check against?
The US IRC (International Residential Code) typical limits: a maximum riser height of 7¾" and a minimum tread depth of 10". Local amendments vary, so confirm with your local building department before construction.
Related tools
From the blog
Update history
- 2026-09-01 Launched: stair calculator with uniform riser-height sizing, stair angle, and a US IRC code-compliance check. Entirely client-side.