Calculate stair parameters including rise, run, angle, and stringer length. Design safe, code-compliant stairs with precision measurements and comprehensive options.
Basic Stair Dimensions
• Rise: Vertical height of each step
• Run: Horizontal depth of each step
• Total Rise: Floor to floor height
Comprehensive Stair Measurements
• Number of Steps
• Stringer Length
• Headroom Clearance
• Handrail Requirements
Stairs are essential architectural elements that must be designed with precision to ensure safety and compliance with building codes. Our comprehensive stair calculator helps you determine all the critical measurements needed for proper stair construction, including rise, run, angle, and stringer length.
Proper stair design involves understanding the relationship between various components and adhering to established safety standards. The calculator provides both basic and comprehensive calculation modes to accommodate different project requirements and complexity levels.
| Component | Definition | Code Requirements |
|---|---|---|
| Rise (Riser) | Vertical distance between consecutive steps | Maximum 7.75 inches (19.7 cm) |
| Run (Tread) | Horizontal depth of each step | Minimum 10 inches (25.4 cm) |
| Total Rise | Overall vertical height of the staircase | Varies by application |
| Total Run | Overall horizontal distance of the staircase | Calculated based on number of treads |
| Nosing | Projection of tread beyond the riser | 0.75-1.25 inches (1.9-3.2 cm) |
| Headroom | Vertical clearance above the stair | Minimum 6 feet 8 inches (203.2 cm) |
| Stair Width | Horizontal width of the stair | Minimum 36 inches (91.44 cm) |
The fundamental principle of stair design is maintaining consistency in rise and run measurements throughout the entire staircase. Variations in step dimensions can cause trips and falls, making uniform measurements a critical safety requirement.
The relationship between rise and run follows the general rule that the sum of one rise plus one run should equal 17-18 inches (43-46 cm) for comfortable use. This relationship, known as the "18-inch rule," ensures that the stair angle falls within the optimal range for safe and comfortable climbing.
Building codes vary by jurisdiction, but most follow similar principles for residential and commercial applications. Residential stairs typically allow steeper angles and smaller dimensions compared to commercial stairs, which must accommodate higher traffic volumes and accessibility requirements.
Handrails are required for stairs with more than 30 inches (76 cm) of total rise and must be positioned between 34-38 inches (86-97 cm) above the tread nosings. Guard rails must be at least 34 inches (86 cm) high for residential applications and 42 inches (107 cm) for commercial use.
Stringers are the structural supports that carry the load of the stairs and must be properly designed for the intended use. The calculator determines the optimal stringer length and angle based on your specific measurements, ensuring adequate structural support.
Standard stringer mounts attach to the top of the floor structure, while flush mounts integrate into the floor system for a cleaner appearance. The choice affects the overall stair geometry and should be considered during the design phase.
Headroom restrictions may require modifications to the basic stair design, potentially affecting the stair angle or requiring intermediate landings. Our comprehensive calculator accounts for these factors when headroom limitations are specified.
Tread thickness affects the overall rise calculation and must be considered when treads overhang the risers. The calculator automatically adjusts calculations when tread thickness is specified, ensuring accurate final dimensions.