DIY

Staircase Calculator

Built by Kevin Glover · @gloverbuilds · Verified formula

Calculate stair rise, run, and number of steps from floor-to-floor height. Code compliant. Free calculator.

📅 Updated April 2026 ✅ Formula verified 📖 4 min read 🆓 Free · No sign-up

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How to Use This Calculator
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Staircase Code Requirements

IRC residential code: max riser 7.75 inches, min tread 10 inches, max variation between risers 3/8 inch. The comfort formula: riser + tread = 17-18 inches. A 7-inch riser with 11-inch tread produces the most natural stride. Minimum width: 36 inches. Handrails required with 4+ risers.

Calculating Steps and Run

Divide total height by target riser to get step count. For 9-foot ceilings (108 inches): 108 / 7 = 15.4, round to 15 steps at 7.2 inches each. Total run = (steps - 1) x tread = 14 x 11 = 154 inches (12.8 feet). This determines the floor space your staircase needs — critical for renovation planning.

⚡ CalcWolf Insight

Inconsistent riser heights are the leading cause of stair falls. Building code limits variation to 3/8 inch because even tiny inconsistencies trip people — your foot expects every step to be identical.

Frequently asked questions

How many steps for a 9-foot ceiling?▾

14-15 steps. Divide total height (108 inches) by target riser (7-7.5 inches). With 15 steps: each riser is 7.2 inches, well within code limits.

What is the ideal stair riser height?▾

7 inches is the most comfortable, paired with an 11-inch tread. This combination meets all building codes and produces a natural walking stride. Never exceed 7.75 inches per code.

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Kevin Glover · @gloverbuilds

Founder, CalcWolf · GLVTS · Blickr

All formulas sourced from primary references — IRS publications, peer-reviewed research, and official standards. Results are tested against independent reference calculators before publishing. Rates and brackets updated when official sources change. Editorial policy →