Stair anatomy — total rise, riser, tread, and run, and how rise sets the number of steps

Total rise (floor to floor) sets everything: risers = ⌈rise ÷ 7¾″⌉, treads = risers − 1, run = treads × tread depth. A 9-ft floor → 15 risers @ 7.2″, 14 treads, 154″ run — and every riser must be equal.

A side elevation of a stair flight labeling the parts of stair geometry. The total rise is the vertical distance from finished floor to finished floor; the total run is the horizontal distance the stair covers; one riser is the height of a single step (about 7¼ inches) and one tread is its depth (about 11 inches). The number of risers equals the total rise divided by the maximum 7¾-inch riser, rounded up; the number of treads is one less than the risers; and the total run is the tread count times the tread depth. For a 9-foot (108-inch) floor-to-floor that is 15 risers at 7.2 inches, 14 treads at 11 inches, and a 154-inch run. Every riser in a flight must be equal. — Source: 2021 IRC R311.7 (stair geometry)

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A side elevation of a stair flight labeling the parts of stair geometry. The total rise is the vertical distance from finished floor to finished floor; the total run is the horizontal distance the stair covers; one riser is the height of a single step (about 7¼ inches) and one tread is its depth (about 11 inches). The number of risers equals the total rise divided by the maximum 7¾-inch riser, rounded up; the number of treads is one less than the risers; and the total run is the tread count times the tread depth. For a 9-foot (108-inch) floor-to-floor that is 15 risers at 7.2 inches, 14 treads at 11 inches, and a 154-inch run. Every riser in a flight must be equal.

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    <img src="https://remodelcalculators.com/api/figure-embed/stair-rise-run-anatomy" alt="A side elevation of a stair flight labeling the parts of stair geometry. The total rise is the vertical distance from finished floor to finished floor; the total run is the horizontal distance the stair covers; one riser is the height of a single step (about 7¼ inches) and one tread is its depth (about 11 inches). The number of risers equals the total rise divided by the maximum 7¾-inch riser, rounded up; the number of treads is one less than the risers; and the total run is the tread count times the tread depth. For a 9-foot (108-inch) floor-to-floor that is 15 risers at 7.2 inches, 14 treads at 11 inches, and a 154-inch run. Every riser in a flight must be equal." width="800" height="520" style="width:100%;height:auto;border:0" loading="lazy">
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