Enter your total rise to get the number of steps, the exact rise and run of each step, and the stringer length — using safe, code-friendly stair proportions.
Stairs are all about dividing your total rise — the floor-to-floor height — into equal steps that are comfortable and safe to climb. You pick a target step height (rise), the calculator finds the whole number of steps that gets closest to it, then works out the exact rise per step, the total run, and the diagonal stringer length you'll cut.
1. Number of risers = total rise ÷ target rise, rounded to a whole number.
2. Actual rise per step = total rise ÷ number of risers.
3. Treads = risers − 1 (the top landing is the last "step").
4. Total run = treads × run. Stringer = √(rise² + run²).
Most U.S. residential codes (IRC) allow a maximum rise of 7¾ in and require a minimum run of 10 in. A long-standing comfort rule is that 2 × rise + run ≈ 24–25 in. This calculator flags your design if the rise or the rise-plus-run check falls outside the usual safe range — but always confirm against your local code.
| Measure | Comfortable | Typical code limit |
|---|---|---|
| Step rise | ~7 in | ≤ 7.75 in |
| Tread run | ~11 in | ≥ 10 in |
| 2 × rise + run | 24–25 in | — |
Every step in a flight should be the same height — uneven steps are a major trip hazard and usually a code violation. This calculator keeps all steps equal by design. For structural stringers, handrails, and landings, follow your local building code and, for anything load-bearing, have the design checked.