Stair Calculator
Risers, treads, and total run from the total rise.
Example
You enter
- Total rise (in) 108
- Preferred riser height (in) 7.5
You get
- Risers 14
- Treads 13
- Riser height 7.714 in
- Total run 130 in
Checked against published worked examples from: Journal of Light Construction (JLC); Naval Education and Training Professional Development and Technology Center.
Details, formula, and sources
ScopeWith the riser count raised until no riser exceeds the IRC R318.7.5.1 [R311.7.5.1 in IRC 2021] 7-3/4 in maximum. Headroom is not computed.
Formula or tableRiser height and tread depth from total rise / number of risers; IRC 2024 §R318.7.5 [R311.7.5 in IRC 2021] residential limits 7-3/4″ max riser, 10″ min tread (the 7″ / 11″ pair is the commercial IBC §1011.5.2 rule).
Source and editionIRC 2024 (International Residential Code). §R318.7 [R311.7 in IRC 2021].
Free accessFree read-only access at codes.iccsafe.org.
What governsEstimate. AHJ and licensed structural engineer govern.
API field namestotal_rise_in, preferred_riser_height_in, risers, treads, riser_height_in, total_run_in
- Standard riser max 7-3/4 in residential per IRC §R318.7.5.1 [R311.7.5.1 in IRC 2021]IRC 2024
- Standard tread min 10 in residential per IRC §R318.7.5.2 [R311.7.5.2 in IRC 2021]IRC 2024