Stairs for a 10 ft (120 in) total rise
A 10 ft (120 in) total rise needs 16 risers of 7-1/2 inches and 15 treads. At 10 inch treads the run is 150 inches (12 ft 6 in) and each stringer is about 192-1/16 inches (16 ft 1/16 in) along the slope.
How to work it out
- 120 in ÷ 7.75 in max = 15.48 → round up to 16 risers, each 120 in ÷ 16 = 7-1/2 in
- 15 treads × 10 in = 150 in run · √(120² + 150²) = 192-1/16 in along the slope
- Comfort check: 2 × 7-1/2 in + 10 in = 25 in (24–26 in is comfortable) · stair angle 36.9 degrees
- Throat: 11-1/4 in board − 6 in notch depth = 5-1/4 in
- Tread board: 10 in tread + 3/4 in nosing + 0 in riser board = 10-3/4 in
- Top level cut: 7-1/2 in riser + 1 in tread − 0 in top finish = 8-1/2 in below the upper subfloor
A 10 ft rise turns up between floors with 9 ft ceilings, on split-level decks and on steep sites. Fifteen risers would be 8 in each, so the flight needs sixteen — and 120 divides evenly by 16, giving a clean 7½ in riser with no fraction to chase.
Adjust for your project
More options: Max riser · Spacing · Stringer board …
- Steps to cut
- 15 steps to cut in each stringer + the upper floor is the top step
- Total run (how far the stairs reach out)
- 150 in (12 ft 6 in)
- Stringer length (along the slope)
- 192-1/16 in (16 ft 1/16 in)
- Stringers needed
- 4 stringers
- Stringer stock to buy
- 4 × 2×12 × 18 ft
- Tread board depth to buy (tread + nosing + riser board)
- 10-3/4 in
- Drop the stringer (trim off the bottom)
- 1 in
- Top level cut, measured down from the top surface
- 8-1/2 in
- Wood left below the notches (throat)
- 5-1/4 in
| Item | What to buy | Notes |
|---|---|---|
| Stringers | 4 × 2×12 × 18 ft | Straight boards with no big knots along the bottom edge, where the wood is in tension. |
| Treads | 15 treads, each 36 in long × 10-3/4 in deep | Depth = tread + nosing + riser board. |
| Hardware | Hangers or a hanger board at the top, fastened to the header or rim; screws for the treads and risers | Plus a handrail on at least one side — four or more risers (2021 IRC R311.7.8). |
Where to mark each step (height above the bottom)
| Step | Height above the bottom | Guard on open sides? |
|---|---|---|
| Tread 1 | 7-1/2 in | — |
| Tread 2 | 15 in | — |
| Tread 3 | 22-1/2 in | — |
| Tread 4 | 30 in | — |
| Tread 5 | 37-1/2 in | Yes — over 30 in |
| Tread 6 | 45 in | Yes — over 30 in |
| Tread 7 | 52-1/2 in | Yes — over 30 in |
| Tread 8 | 60 in | Yes — over 30 in |
| Tread 9 | 67-1/2 in | Yes — over 30 in |
| Tread 10 | 75 in | Yes — over 30 in |
| Tread 11 | 82-1/2 in | Yes — over 30 in |
| Tread 12 | 90 in | Yes — over 30 in |
| Tread 13 | 97-1/2 in | Yes — over 30 in |
| Tread 14 | 105 in | Yes — over 30 in |
| Tread 15 | 112-1/2 in | Yes — over 30 in |
| Upper floor | 120 in | Yes — over 30 in |
One step fewer or more
| Risers | Each step | Treads | Tread depth | Total run | Check |
|---|---|---|---|---|---|
| 15 risers | 8 in | 14 | 10 in | 140 in | Risers too tall |
| 16 risers (shown) | 7-1/2 in | 15 | 10 in | 150 in | OK |
| 17 risers | 7-1/16 in | 16 | 10 in | 160 in | OK |
- Stair guard required from tread 5: it sits more than 30 in above the bottom, so open sides need a guard at least 34 in high (IRC R312.1.1, R312.1.2). This assumes the floor beside the stair is level with the bottom landing — measure where it falls away.
- Headroom: keep at least 6 ft 8 in clear above the line of the nosings along the whole flight (IRC R311.7.2). Enter the upper floor thickness to get the shortest ceiling opening.
- Leave a landing at the bottom (and the top, unless it is the floor itself) at least 36 in deep and as wide as the stair (IRC R311.7.6).
- Trim 1 in off the bottom of each stringer (one tread thickness) so the first step comes out the same 7-1/2 in as the rest.
Stringers and stock for a 120 in rise, by stair width
| Stair width | Stringers needed | Stringer stock to buy |
|---|---|---|
| 36 in | 4 stringers | 4 × 2×12 × 18 ft |
| 42 in | 4 stringers | 4 × 2×12 × 18 ft |
| 48 in | 4 stringers | 4 × 2×12 × 18 ft |
| 60 in | 5 stringers | 5 × 2×12 × 18 ft |
What to know about stairs for a 10 ft rise
Ten feet is still under the 12 ft 7 in (151 in) maximum rise for one flight in IRC R311.7.3, so a straight flight is allowed without a landing. The 7½ in risers leave ¼ in under the 7¾ in limit in R311.7.5.1, and the 10 in treads are at the R311.7.5.2 minimum, which means ¾ to 1¼ in nosings on every tread. With sixteen risers a handrail is required (R311.7.8), and any open side of the upper treads more than 30 in above the floor needs a guard at least 34 in high (R312.1).
Stringers at this length are a buying problem. Each is about 16 ft along the slope, so the stock line asks for 18 ft 2×12s, which many yards keep in small numbers and which are hard to find straight. That is one reason builders split a rise like this with a landing: two shorter flights use common 10 or 12 ft boards and give a resting point halfway up.
The footprint is 150 in — 12½ ft of floor plus space at both ends — and headroom must stay at or above 6 ft 8 in over every tread (R311.7.2). Check the ceiling opening before you cut; a stair this long passes under a lot of framing.
Compare Stair stringers for a 9 ft rise, which is at the riser limit, and Stair stringers for an 8 ft rise. The stair stringer guide covers marking sixteen identical notches with stair gauges.
Different size? Use the full Stair Stringer Calculator.
What you’ll need
- Framing squareBudget price
The tool for laying out stair stringers and rafters: rise on one leg, run on the other.
See options on Amazon (opens in a new tab) - Stair gaugesBudget price
Small brass or steel buttons that clamp to a framing square so every rise and run you mark is identical.
See options on Amazon (opens in a new tab) - Circular saw (7¼ in)Mid-range price
The most versatile first power saw: crosscuts framing lumber, rips boards and, with a straightedge, breaks down plywood sheets.
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Frequently asked questions
How long is the stringer for a 10 ft rise with 10½ in treads?
About 198 inches (16 ft 6 in), with 157-1/2 inches (13 ft 1-1/2 in) of run — 4 × 2×12 × 18 ft. The extra half inch per tread adds 7½ inches to the footprint.
How many risers for a 120 in rise with a 7 in maximum?
18 risers of 6-11/16 inches and 17 treads, for 170 inches (14 ft 2 in) of run at 10 inch treads — 4 × 2×12 × 20 ft.
Other common sizes
- How many steps for a 3 ft deck — 5 risers
- How many steps for a 2 ft deck — 4 risers
- How many steps for a 30 in deck — 4 risers
- How many steps for a 4 ft deck — 7 risers
- Stair stringers for an 8 ft rise — 13 risers
- Stair stringers for a 2.7 m rise — 15 risers
Sources
- International Code Council, 2021 International Residential Code, Chapter 3 Building Planning (opens in a new tab) — R311.7.1 width (36 in), R311.7.2 headroom (6 ft 8 in), R311.7.3 vertical rise of a flight (12 ft 7 in), R311.7.5.1 risers (7¾ in; open risers more than 30 in up must not pass a 4 in sphere), R311.7.5.2 treads (10 in), R311.7.5.3 nosings (¾–1¼ in unless the tread is 11 in or deeper), R311.7.6 landings (36 in deep), R311.7.8 handrails, R312.1 guards.
- American Wood Council, DCA 6 Prescriptive Residential Wood Deck Construction Guide (2015 IRC edition) (opens in a new tab) — Stair requirements, Figures 28, 29, 31 and 34: 2×12 minimum stringers; cut stringers span no more than 6 ft 0 in and keep at least 5 in below the notches; at least three cut stringers at no more than 18 in on center; sloped hangers or a hanger board at the top; an intermediate landing where the total rise exceeds 12 ft; stringers bear on footings below frost depth, not on pads or patios that aren’t founded that deep.