Building Stairs Safely: Terminology and Rules

Building a staircase is one of the most challenging—and rewarding—DIY projects. Unlike a wall or a floor, stairs have critical safety dimensions that must be followed. Our calculator is designed to simplify the complex math involved and check your design against common safety standards, ensuring your project is both beautiful and secure.

Key Stair Terminology

• Total Rise: The total vertical distance the staircase needs to cover, from the surface of the lower floor to the surface of the upper floor.
• Riser: The vertical part of a step. Our calculator determines the optimal height for each riser.
• Tread: The horizontal part of a step that you walk on.
• Total Run: The total horizontal distance the staircase will occupy.
• Stringer: The structural "backbone" of the staircase, typically a 2x12 board, into which the treads and risers are cut.
• Headroom: The vertical distance from the top of a tread to the ceiling above it. This should be at least 6' 8" (203 cm) at all points.

The Golden Rules of Stair Design

Most building codes are based on ensuring a staircase is comfortable and not too steep. Our calculator checks against these common rules:

1. The 2R + T Rule: The sum of two risers and one tread (2R + T) should be between 24 and 25 inches (61-63.5 cm). This ensures a comfortable gait.
2. Riser Height Limit: Risers are typically no more than 7.75 inches (19.7 cm).
3. Tread Depth Minimum: Treads should be at least 10 inches (25.4 cm) deep to provide adequate foot space.

Our calculator will give you a "Pass" or "Fail" based on these principles, helping you adjust your design for safety.

Related Construction Calculators

A staircase is just one part of a construction project. To determine the area of the room your stairs will be in, use our Square Footage Calculator. If you're building a concrete landing at the bottom of your stairs, you'll need our Concrete Calculator to estimate the material required.