Standard Stair Rise and Run

Stair calculations have gotten complicated with all the code requirements, safety considerations, and ergonomic standards flying around. As someone who has framed stairs for every building type, I learned everything there is to know about getting rise and run measurements right. Today, I will share it all with you.

Understanding Rise and Run

Probably should have led with this section, honestly—rise is the vertical distance between steps, and run is the horizontal depth of the tread. Together, they define the stair slope.

Standard Measurements

That’s what makes proper stair design endearing to us safety-conscious builders—consistency prevents accidents:

Rise

• Residential stairs: 7 to 7.75 inches
• Commercial buildings: 4 to 7 inches
• Consistency is crucial—varying rises cause trips and falls

Run

• Residential buildings: 10 to 11 inches
• Commercial buildings: at least 11 inches (code requirement)
• Sufficient run provides room for the entire foot

Calculating Dimensions

• Total run = individual run × number of steps (not including upper floor)
• Total rise = individual rise × number of steps
• Sum should match height between lower and upper floors
• Round measurements to ensure step uniformity

Stair Slope

Ideal angle is 30 to 37 degrees. Steeper stairs are harder to climb and more dangerous. Gentler slopes take more floor space. A 7-inch rise with 11-inch run is a commonly accepted ratio.

Building Codes

The International Residential Code (IRC) sets maximum and minimum measurements. Always consult local codes as they may have more specific requirements. Meeting code ensures safety and compliance.

Special Considerations

• Outdoor stairs: Include drainage and slip-resistant treads
• Visibility: Use contrasting colors for depth perception
• Width: Minimum 36 inches residential, 44 inches commercial

Ergonomics and Safety

• Handrails at 34 to 38 inches from tread
• Adequate lighting reduces accidents
• Nosing should project slightly for extra step surface
• Rounded nosings reduce injury risk

Materials

• Wood: Warm look but may wear over time
• Concrete: Durable but cold
• Steel: Modern but may be noisy
• Consider carpet or anti-slip strips for added safety

Key Points

• Measure rise and run accurately
• Ensure uniformity in all steps
• Consult building codes
• Use proper materials and maintain them
• Include handrails and adequate lighting