Answer
One flight, cut as a single stringer.
3-step stair stringer
Total rise it covers
12into23in
- Risers
- 3
- Typical total rise
- 21in21.000 in
- Board length
- 4ft
Range
Every total rise this stringer covers
Pick your own total rise. Every row is cut with the same number of risers.| Total rise | Riser | Tread | Total run | Stringer | Marked | Board | Result |
|---|---|---|---|---|---|---|---|
| 12in | 4in | 14in | 28in | 307/16716in | 4311/161116in | 5ft | Within |
| 13in | 45/16516in | 14in | 28in | 307/878in | 4315/161516in | 5ft | Within |
| 14in | 411/161116in | 14in | 28in | 315/16516in | 441/414in | 5ft | Within |
| 15in | 5in | 14in | 28in | 313/434in | 445/858in | 5ft | Within |
| 16in | 55/16516in | 14in | 28in | 321/414in | 4415/161516in | 5ft | Within |
| 17in | 511/161116in | 1311/161116in | 275/16516in | 323/16316in | 443/838in | 5ft | Within |
| 18in | 6in | 13in | 26in | 315/858in | 4215/161516in | 5ft | Within |
| 19in | 65/16516in | 125/16516in | 2411/161116in | 311/818in | 419/16916in | 4ft | Within |
| 20in | 611/161116in | 1111/161116in | 235/16516in | 303/434in | 405/16516in | 4ft | Within |
| 21in | 7in | 11in | 22in | 307/16716in | 391/818in | 4ft | Within |
| 22in | 75/16516in | 105/16516in | 2011/161116in | 303/16316in | 38in | 4ft | Within |
| 23in | 711/161116in | 10in | 20in | 301/212in | 3713/161316in | 4ft | Within |
Solution
Every dimension of this flight
Worked at a total rise of 21.00 inches.| Dimension | Value |
|---|---|
| Typical total rise | 21in21.00 in |
| Risers | 3 |
| Riser height | 7in7.000 in |
| Treads | 2 |
| Tread run | 11in11.000 in |
| Total run | 22in22.000 in |
| One step along the edge | 131/16116in13.038 in |
| Marked length | 391/818in39.115 in3 ft 3.12 in |
| Stringer length | 307/16716in30.414 in2 ft 6.41 in |
| Board length | 4ft |
| Angle | 32.5° |
| Bottom cut deduction | 1in1.000 in |
Cut list
The marks, bottom to top
Measured along the edge of the board from the foot, after the bottom cut.- Marked length
- 391/818in39.115 in3 ft 3.12 in
- Bottom cut deduction
- 1in
- 7in×11in 131/16116inFrom the foot
- 7in×11in 261/16116inFrom the foot
- 7in×11in 391/818inFrom the foot
Code
Each figure against the limit it has to meet
| Dimension | Limit | Code | Result |
|---|---|---|---|
| Riser height, maximum | 73/434in | IRC 2021 (residential) | Within |
| Tread depth, minimum | 10in | IRC 2021 (residential) | Within |
| Stair width, minimum | 36in | IRC 2021 (residential) | Within |
| Riser height, minimum | 4in | ADA 2010504.2 | Within |
| Riser height, maximum | 7in | ADA 2010504.2 | Within |
| Tread depth, minimum | 11in | ADA 2010504.2 | Within |
| Nosing projection, maximum | 11/212in | ADA 2010504.5 | Within |
Asked about this
Questions people search for
How high will a 3-step stringer go?
A 3-step stringer covers 12 to 23 inches of total rise, floor to floor. Below that the risers fall under the 4 inch minimum; above it they pass 7 3/4 inches.
How long a board do you need for a 3-step stringer?
At a 21 inch total rise the marks run 39.115 inches along the edge of the board, so the shortest board that takes them with the top and bottom cuts is 4 feet.
How do you lay out a 3-step stringer?
Set a framing square to 7.000 inches on the tongue and 11.00 inches on the blade and step it 3 times along the board, then drop the bottom cut by one tread thickness. Every mark is listed on this page, and the stringer layout page shows where each one goes.
Next door
Other step counts
Source
Where the limits come from
2 sources, with the date each was read
- Code limits: IRC 2021 (residential), retrieved from https://www.co.routt.co.us/DocumentCenter/View/15202 on 2026-09-18. Numeric limits only; no code text is reproduced.
- Code limits: ADA 2010, 504.2, 504.5, retrieved from https://www.access-board.gov/aba/chapter/ch05/ on 2026-09-18. Numeric limits only; no code text is reproduced.
Building codes are adopted and amended locally. Confirm every figure with the code your jurisdiction has adopted before you cut.
Updated September 2026