How do you calculate stair riser height?

Divide the total vertical rise by the number of risers.

How do you calculate stair run?

Divide the total horizontal run by the number of treads or runs used in the selected layout convention.

Does this design the stringer?

No. It generates layout geometry only and does not verify structural capacity, code compliance or support details.

Stair layout geometry

Staircase Stringer Layout Calculator

Turn total rise and run into a step-by-step tread and riser schedule. The tool is for layout planning only and intentionally does not perform structural stair design.

Stair geometry

Total rise

Total horizontal run

Number of risers

Number of treads

Tread overhang

Unit

Enter total rise, run and step counts.

Step layout

Riser height——

—Tread depth

—Stair pitch

—Stringer slope length

—2R + T

Step	Riser elevation	Tread position

—

Stringer layout methodology

The total rise is divided by the number of risers, while the total horizontal run is divided by the number of treads. The pitch is then obtained from the resulting rise/run ratio. A layout schedule gives cumulative positions for each step.

Riser = total rise ÷ risers
Tread = total run ÷ treads
Pitch = atan(riser ÷ tread)
Stringer slope = √(rise² + run²)

Example

With 3.0 m total rise and 18 risers, the riser height is 0.1667 m. With 4.2 m run and 17 treads, the tread depth is about 0.2471 m.

Structural limitation

The output is a geometric layout schedule. Stringer thickness, support, connection, reinforcement, loading and applicable stair requirements must be checked separately.

Frequently Asked Questions

Can risers and treads have different counts?

Yes, because the first or top landing may affect how the geometry is counted.

Can overhang be zero?

Yes.

Does this verify stair-code compliance?

No. It does not apply local code rules.