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Staircase Calculator

Tread Material

Floor-to-Floor Height (in)

Available Run Space (ft)

Stair Width (in)

Result

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◆ LIVE 3D PREVIEW

Rise/Run

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Stringer Length

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IRC Stair Code Requirements

Max rise: 7-3/4 in • Min run: 10 in • Min width: 36 in • Min headroom: 6 ft 8 in • Nosing: 3/4 to 1-1/4 in projection • Handrail: 34-38 in height. Rise must be consistent within 3/8 in between steps.

How to Calculate Staircase

Use this free staircase 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.

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💡 Pro Tips — Staircase

IRC code: Max riser 7¾", min tread 10", headroom 6'8" minimum.
All risers must be equal: Max 3/8" variation between any two risers per code.
The comfort formula: 2×Riser + Tread = 24-25". This is what feels natural.
3 stringers for wide stairs: Over 36" wide, add a center stringer to prevent bounce.
Outdoor stairs: Never use untreated pine. Use PT lumber or composite.

❓ 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" ✓