Stair Calculator

Stairs are unforgiving — an uneven riser trips people and fails inspection. The Stair Calculator takes the total floor-to-floor rise and your target riser and tread, then returns the whole-number step count, the even actual riser height, the total run, and the diagonal stringer length.

It checks the result against typical IRC limits (riser 4"–7.75", tread ≥10", headroom 6'8") and works in inches, feet, meters or centimeters so your cuts match the plans.

• Step count: Whole steps from total rise.
• Even riser: Actual riser = rise ÷ steps.
• Total run: (steps − 1) × tread.
• Stringer: √(rise² + run²) diagonal.
• Code checks: Riser/tread/headroom flags.
• Unit toggle: in, ft, m, cm.
• Report & export: Copy or download as text, CSV or JSON.

1. Pick unit. Inches, feet, meters or cm.
2. Enter total rise. Floor-to-floor height.
3. Enter riser & tread. Your target dimensions.
4. Read results. Steps, riser, run, stringer, flags.
5. Export. Copy or download.

Example 1 — 9 ft floor. 108" rise, 7" riser, 10" tread → 15 steps (7.2" riser), 140" run, 178.4" stringer.

Example 2 — 8 ft. 96" rise, 7.5" riser → 13 steps (7.38" riser), 120" run.

Example 3 — Too steep. 108" rise, 8.5" riser → fails (over 7.75"); lower the riser.

Example 4 — Code max. 108" rise, 7.75" riser → 14 steps (7.71" riser), 130" run.

Example 5 — Metric. 2.7 m rise, 0.18 m riser, 0.25 m tread → 15 steps.

• Even steps: No tripping from uneven risers.
• Correct stringer: Diagonal length, not horizontal.
• Code-aware: Flags out-of-range riser/tread.
• Unit-flexible: Cut to your unit.
• Private: No account, nothing uploaded.