A 2,700 mm floor-to-floor rise takes 15 risers of 180 mm with 270 mm treads, a total run of 3,780 mm at 33.7°.
| Total rise (mm) | Risers | Riser height (mm) | Tread depth (mm) | Treads | Total run (mm) | Angle (°) |
|---|---|---|---|---|---|---|
| 2,000 | 11 | 181.8 | 266 | 10 | 2,664 | 34.3 |
| 2,100 | 12 | 175.0 | 280 | 11 | 3,080 | 32.0 |
| 2,200 | 12 | 183.3 | 263 | 11 | 2,897 | 34.8 |
| 2,300 | 13 | 176.9 | 276 | 12 | 3,314 | 32.6 |
| 2,400 | 13 | 184.6 | 261 | 12 | 3,129 | 35.3 |
| 2,500 | 14 | 178.6 | 273 | 13 | 3,547 | 33.2 |
| 2,600 | 14 | 185.7 | 259 | 13 | 3,361 | 35.7 |
| 2,700 | 15 | 180.0 | 270 | 14 | 3,780 | 33.7 |
| 2,800 | 16 | 175.0 | 280 | 15 | 4,200 | 32.0 |
| 2,900 | 16 | 181.3 | 268 | 15 | 4,013 | 34.1 |
| 3,000 | 17 | 176.5 | 277 | 16 | 4,433 | 32.5 |
| 3,100 | 17 | 182.4 | 265 | 16 | 4,245 | 34.5 |
| 3,200 | 18 | 177.8 | 274 | 17 | 4,666 | 32.9 |
| 3,300 | 18 | 183.3 | 263 | 17 | 4,477 | 34.8 |
| 3,400 | 19 | 178.9 | 272 | 18 | 4,898 | 33.3 |
| 3,500 | 19 | 184.2 | 262 | 18 | 4,708 | 35.2 |
| 3,600 | 20 | 180.0 | 270 | 19 | 5,130 | 33.7 |
How it is computed
Risers = total rise ÷ target riser, rounded; riser height = total rise ÷ risers. Tread depth comes from the comfort rule 2 × riser + tread ≈ 630 mm. There is one tread fewer than risers, since the top floor is the last step; total run = treads × tread depth. Check your local building code for maximum riser and minimum tread.
FAQ
What is the 2R + T rule?+
A stride rule: two risers plus one tread should equal about 630 mm (24 to 25 in). Stairs that follow it feel natural to climb.
What are the code limits?+
Many residential codes cap risers at about 196 to 200 mm (7¾ in) and require treads of at least 235 to 255 mm (9 to 10 in). Check the code where you build.