Stair Calculator

Calculate stair dimensions, steps, rise, run, angle, and building code compliance

Total Rise (inches) Floor to floor height

Total Run (inches) Horizontal distance available

Number of Steps Leave blank to auto-calculate

Tread Thickness (inches)

Stringer Width (inches)

Minimum Headroom (inches) Building code minimum: 80"

Stair Width (inches) Code minimum: 36"

Calculation Method

Number of Steps

Unit Rise

Unit Run (Tread)

Stair Angle

Stringer Length

Total Tread Area

Total Riser Area

Recommended Stringers

Ideal ratio: 2 x Rise + Run = 24-25 inches. Common comfortable ratio is 7" rise with 11" run.

All rises should be identical within 3/8". Variation can cause tripping hazards.

Use 2x12 lumber for stringers. Space stringers max 16" on center for 5/4" treads.

Attach stringers with joist hangers or ledger board. Use appropriate fasteners for load.

Minimum 6'8" headroom throughout stair run. Check local codes for requirements.

Install handrails 34-38" high. Guardrails required for stairs over 30" high.