Stair Rise and Run Calculator
This calculator helps determine safe and comfortable stair dimensions by calculating optimal rise (vertical height) and run (horizontal depth) for each step, ensuring compliance with building codes and ergonomic standards.
Calculator
Results
| Measurement | Value |
|---|---|
| Rise per Step | |
| Run per Step |
FAQs
What's the ideal rise/run ratio?
The optimal ratio is typically 7-7.5" rise with 10-11" run. Most building codes require a maximum rise of 7.75" and minimum run of 10". The 7/11 ratio is considered comfortable for most users while maintaining safety standards.
How does calculator ensure code compliance?
Our calculator checks inputs against International Building Code standards, flagging values that exceed maximum rise (7.75") or minimum run (10"). However, always verify local regulations as codes may vary by municipality.
Can I use this for spiral stairs?
This calculator is designed for straight-run stairs. Spiral stairs have different code requirements and dimensional calculations due to their rotating design and varying tread widths.
How to measure total vertical height?
Measure from finished floor to finished floor vertically (plumb line). Include floor coverings in your measurement. Use laser measure for accuracy or traditional methods with multiple checks for consistency.
What if my results exceed code limits?
Adjust number of steps to achieve compliant dimensions. More steps decrease rise/increase run. Ensure all steps have uniform dimensions - variations greater than 3/8" can create tripping hazards.
Does run include nosing overhang?
No, run is measured from nosing to nosing horizontally. Most codes allow maximum 1.25" nosing overhang beyond run measurement. The overhang doesn't count toward minimum run requirements.
How important is step consistency?
Critical for safety. Building codes typically mandate that rise/run variation between steps cannot exceed 3/8". Consistent dimensions prevent missteps. Always double-check measurements throughout installation.
Can I use decimals in measurements?
Yes, our calculator accepts decimal inputs (to 1/8" precision). However, actual construction typically uses fractions. 0.125 = 1/8", 0.25 = 1/4", 0.375 = 3/8", etc. Convert decimals accordingly during building.
What's the maximum allowed stairs without landing?
Most codes allow maximum 12 feet vertical rise (about 18-20 steps) before requiring a landing. Landings must be at least as wide as stairway and minimum 36" long in direction of travel.
How to adjust for existing stringers?
If working with existing structure, measure actual rise/run of current steps. Use calculator to determine needed adjustments. Note that modifying stringers may require complete replacement to maintain structural integrity.