Stair Calculator
Calculate stair dimensions including rise, run, number of steps, stringer length, and angle. Checks building code compliance.
Stair Dimensions
feet
feet
Preferences (Optional)
inches
Leave blank to auto-calculate optimal rise (code: 7-7.75")
Stair Specifications
Number of Risers
-
Number of Treads
-
Riser Height
-
Tread Depth (Run)
-
Stair Angle
-
Stringer Length
-
Headroom Needed
-
✓ Building Code Check: Passes residential code requirements
Building Code Requirements (IRC Residential)
- Riser height: Max 7.75" (196mm), min 4" (102mm)
- Tread depth: Min 10" (254mm)
- Riser + Tread rule: Should equal 17-18" for comfort
- Headroom: Min 6'8" (2032mm) clearance
- Width: Min 36" (914mm) for residential
- Handrail: Required if 4+ risers, 34-38" height
- Variation: Max 3/8" (9.5mm) difference between any riser
Ad Space - 728x90
How to Calculate Stairs
- Measure total rise - Floor to floor height (including finish floor thickness)
- Calculate number of risers - Total rise ÷ ideal riser height (7"-7.75")
- Calculate riser height - Total rise ÷ number of risers
- Determine tread depth - Total run ÷ (risers - 1), minimum 10"
- Calculate stringer length - √(rise² + run²)
- Verify code compliance - Check all dimensions against local codes
Comfort formula: 2 × Riser + Tread = 24" to 25" (ideal)