Stair Calculator

Stair Calculator

Professional stair design calculator with safety compliance checks. Perfect for builders, architects, and DIY enthusiasts.

Quick Stair Type Presets

Total height from floor to floor

Horizontal distance available

Maximum rise per step (≤ 7.75" recommended)

Minimum tread depth (≥ 10" recommended)

Safety Rules & Compliance

2R + G = 25"
Rise + Run formula for comfort
Rise ≤ 7.75"
Maximum rise height
Run ≥ 10"
Minimum tread depth
Angle ≤ 37°
Maximum stair angle
Consistent steps
All steps must be uniform

About Stair Calculator

Purpose & Functionality

This comprehensive stair calculator helps architects, builders, and homeowners design safe, comfortable, and code-compliant stairs. It automatically calculates optimal dimensions while ensuring adherence to building codes and safety standards across different stair types.

The calculator considers ergonomic principles, building regulations, and accessibility requirements to provide stair designs that are both functional and safe for all users.

Stair Design Principles

Comfort Formula

  • 2R + G = 22-28 inches
  • R = Rise height (vertical step)
  • G = Going/run depth (horizontal step)
  • Optimal range: 24-26 inches
  • Ensures comfortable walking rhythm

Safety Standards

  • Maximum Rise: 7.75 inches (residential)
  • Minimum Run: 10 inches (residential)
  • Maximum Angle: 37 degrees
  • Consistency: All steps must be uniform
  • Handrails: Required for safety

Stair Types & Applications

Building Code Classifications

Residential Stairs:

  • Max Rise: 7.75 inches
  • Min Run: 10 inches
  • Use: Homes and apartments
  • Comfort: High priority

Commercial Stairs:

  • Max Rise: 7.0 inches
  • Min Run: 11 inches
  • Use: Offices and retail
  • Safety: Maximum priority

Key Measurements Explained

Vertical Dimensions

  • Total Rise: Floor-to-floor height
  • Rise Height: Individual step height
  • Number of Steps: Calculated from rise
  • Landing Height: Intermediate platforms

Horizontal Dimensions

  • Total Run: Horizontal distance
  • Run Depth: Individual step depth
  • Stringer Length: Diagonal support beam
  • Landing Depth: Platform dimensions

Building Code Compliance

  • International Building Code (IBC): Sets minimum safety standards
  • Americans with Disabilities Act (ADA): Accessibility requirements
  • Local Building Codes: May have additional requirements
  • Fire Safety Codes: Emergency exit stair requirements
  • Occupancy Loads: Stair capacity requirements

Safety Considerations

Physical Safety

  • Proper rise-to-run ratios
  • Consistent step dimensions
  • Adequate tread depth
  • Proper handrail height
  • Good lighting and visibility

Accessibility

  • ADA compliance requirements
  • Handrail specifications
  • Landing requirements
  • Clear width requirements
  • Emergency egress standards

Common Design Mistakes

  • Inconsistent Steps: Varying rise/run dimensions cause trips
  • Steep Angles: Angles over 37° are difficult to navigate
  • Inadequate Run Depth: Steps too shallow for safe footing
  • Missing Handrails: Essential for safety and accessibility
  • Poor Lighting: Inadequate visibility increases accident risk

Pro Tips

  • • Always consult local building codes before finalizing stair designs
  • • Use the comfort formula (2R + G = 24-26 inches) for optimal user experience
  • • Consider adding intermediate landings for stairs with more than 12 steps
  • • Ensure adequate headroom clearance (minimum 6'8" for residential)
  • • Test stair dimensions with actual users when possible
  • • Remember that wider stairs (36"+ clear width) are more comfortable and safer