Staircase Dimensional Calculator
Calculate structural parameters for stairs, including riser counts, exact step heights, tread runs, deck stringer lengths, and incline angles.
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Calculated Stair Specifications
Number of Risers15
Actual Riser Height6.800 in
Number of Treads14
Total Run Length147.00 in (12.25 ft)
Staircase Angle32.9°
Stringer Board Length178.92 in (14.91 ft)
Layout Derivation Breakdown:
1. Total Rise: 102.00 inches 2. Estimated Risers: Round(102.00 / 7) = 15 3. Actual Riser Height: 102.00 / 15 = 6.800 inches 4. Number of Treads: 15 - 1 = 14 5. Total Run: 14 × 10.5 = 147.00 inches (12.25 ft) 6. Stair Angle: arctan(6.80 / 10.5) ≈ 32.93° 7. Stringer Length: √(102.00² + 147.00²) ≈ 178.92 inches
Frequently Asked Questions
What is the standard riser height for residential stairs?
Building codes typically recommend a maximum riser height of 7.75 inches and a minimum tread run of 10 inches. A target riser height of 7 inches is commonly used for comfort.
Why is the number of treads one less than the number of risers?
The top riser meets the upper deck/floor level, meaning you do not need a tread at the very top. So, Treads = Risers - 1.