OpenTools

Construction tools

Stair Calculator

Plan equal risers, treads, total run, and stringer geometry using locally verified limits you enter.

Stair geometry planner

Measure total finished-floor rise, then enter the limits required by the code and authority for your project.

Project geometry

The example values are editable reference inputs. Confirm adopted code, nosing rules, landings, headroom, guards, and structural details locally.

Geometry with user-entered limits

The calculator uses riser count = round up(total rise ÷ entered maximum rise), divides the measured rise equally, then derives total run and √(total rise² + total run²).

Model codes are adopted and amended locally. The displayed check only compares geometry with the limits you entered; it is not a permit or code decision.

Method & sources

The example assumes one fewer tread than risers for a floor-to-floor stair. Site configuration may differ.

Important limits

  • Measure between finished floor elevations and verify how the upper landing is counted.
  • This does not design or lay out stringer cuts, structure, connections, landings, headroom, nosings, handrails, or guards.
  • Confirm the adopted code and project conditions with the authority having jurisdiction and a qualified professional.

Reviewed references