🌀

Spiral Stair Calculator

Result
—diameter needed
Treads
—
Rotation
—
CalcBuild › Spiral Stair Calculator

How to Calculate Spiral Stair

Use this free spiral stair calculator to get instant, accurate results for your construction project. Simply enter your measurements above and the calculator will automatically compute the result using industry-standard formulas.

Pro Tip: Always add 10-15% extra material to account for waste, cuts, and job-site conditions. This is standard practice recommended by experienced contractors.

Related Calculators

▸ Concrete Stairs▸ Deck Stair▸ Stair▸ Stair Railing▸ Stair Stringer▸ Staircase

💡 Pro Tips — Spiral Stair

❓ Frequently Asked Questions

+What is the max riser height?
7.75 inches per IRC code. Comfortable range is 7-7.25 inches. All risers must be within 3/8" of each other.
+What is the minimum tread depth?
10 inches per IRC code. 11 inches is more comfortable and commonly used.
+How many stringers do I need?
2 for stairs up to 36" wide. Add a center (3rd) stringer for wider stairs to prevent bouncing.
+What is the comfort formula?
2×Riser + Tread should equal 24-25 inches. Example: 7.5" riser + 10" tread = 25" ✓
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🌀

Spiral Stair Calculator

Result
—diameter needed
Treads
—
Rotation
—
CalcBuild › Spiral Stair Calculator

How to Calculate Spiral Stair

Use this free spiral stair calculator to get instant, accurate results for your construction project. Simply enter your measurements above and the calculator will automatically compute the result using industry-standard formulas.

Pro Tip: Always add 10-15% extra material to account for waste, cuts, and job-site conditions. This is standard practice recommended by experienced contractors.

Related Calculators

▸ Concrete Stairs▸ Deck Stair▸ Stair▸ Stair Railing▸ Stair Stringer▸ Staircase
+t.toFixed(0)+''; b.appendChild(tr);c.style.display='block';}
🌀

Spiral Stair Calculator

Result
—diameter needed
Treads
—
Rotation
—
CalcBuild › Spiral Stair Calculator

How to Calculate Spiral Stair

Use this free spiral stair calculator to get instant, accurate results for your construction project. Simply enter your measurements above and the calculator will automatically compute the result using industry-standard formulas.

Pro Tip: Always add 10-15% extra material to account for waste, cuts, and job-site conditions. This is standard practice recommended by experienced contractors.

Related Calculators

▸ Concrete Stairs▸ Deck Stair▸ Stair▸ Stair Railing▸ Stair Stringer▸ Staircase