MyAICalc Logo
MyAICalc Personal AI Calculator Hub
Construction Math

Stair Calculator

Determine the number of steps, actual riser height, total run, stringer length, and incline angle for your stairs.

Input Dimensions

Standard US building code limits the maximum riser height to 7.75 inches (19.7 cm) and minimum tread run to 10 inches (25.4 cm) for safety.

Enter valid dimensions to compute stair configuration.
Construction Math

How to Calculate
Stair Parameters

Designing stairs requires strict adherence to safety standards. The relationship between the height of each step (riser) and the depth of each step (tread) determines the safety and comfort of the stairway.

Total Rise

The primary baseline measurement. Measured vertically from finished floor to finished floor, ignoring intermediate joists.

Blondel Comfort

Ensures that the natural walking stride is respected. Two risers plus one tread run should approximate 24 to 25 inches.

Safety Standards

Adhering to local building codes prevents tripping hazards. Standard limits require rise heights of 7.75" or less.

Key Stair Terminology

  • Total Rise: The vertical distance from the lower floor surface to the upper finished floor surface.
  • Riser (Rise): The vertical face of each step. The standard height is typically 7 to 7.5 inches.
  • Tread (Run): The horizontal surface of each step that you step on. The standard run depth is typically 10 to 11 inches.
  • Stringer: The structural boards on either side of the staircase that support the treads and risers.

Standard Stair Layout Comfort Rules:

  • • Riser Rule: Keep risers between 7 inches and 7.75 inches for domestic structures.
  • • Tread Depth Rule: Run depth should never be less than 10 inches to ensure proper foot support.
  • • Uniformity: The greatest riser height or tread run within any flight of stairs must not exceed the smallest by more than 3/8 inch.