Stair calculator: rise, going and pitch (Part K)
The calculator needs JavaScript. The worked example, formula and figures below show exactly how it works, so you can do the sum yourself. A guide, not advice. Check your supplier's or maker's figures before ordering.
Short answer
Worked example
| You enter | Value |
|---|---|
| Total rise | 2,600 mm |
| Stair type | Private (in a home) |
| Fewest risers to compare | 12 |
| Most risers to compare | 17 |
| Headroom guidance | 2 m |
Suggested: 12 risers of 216.7 mm with 241 mm goings
- Limit not yet confirmed Rise of each step (Table 1.1): 0.217 m The limit for this check hasn't been confirmed yet: check the source. England: Approved Document K 2013, Table 1.1 (rise). Check with the source
- Limit not yet confirmed Going of each tread (Table 1.1): 0.241 m The limit for this check hasn't been confirmed yet: check the source. England: Approved Document K 2013, Table 1.1 (going). Check with the source
- Within the guidance Pitch: 41.957 ° England: Approved Document K 2013, para 1.3 / Table 1.1 (pitch). Check with the source
- Within the guidance 2R + G (the normal relationship): 0.674 m England: Approved Document K 2013, Table 1.1 (2R + G). Check with the source
| Result | Value |
|---|---|
| Risers | 12 |
| Treads (risers − 1) | 11 |
| Rise of each step | 216.7 mm |
| Going of each tread | 241 mm |
| 2R + G | 674.3 mm |
| Pitch | 42 ° |
| Total going (plan length of the flight) | 2.65 m |
| Risers | Rise | Going | 2R + G | Pitch | Total going | Rise and going (Table 1.1) | Pitch check | 2R + G |
|---|---|---|---|---|---|---|---|---|
| 12 | 216.7 mm | 241 mm | 674.3 mm | 42 ° | 2.65 m | Limit not yet confirmed | Within the guidance | Within the guidance |
| 13 | 200 mm | 223 mm | 623 mm | 41.9 ° | 2.68 m | Limit not yet confirmed | Within the guidance | Within the guidance |
| 14 | 185.7 mm | 207 mm | 578.4 mm | 41.9 ° | 2.69 m | Limit not yet confirmed | Within the guidance | Within the guidance |
| 15 | 173.3 mm | 193 mm | 539.7 mm | 41.9 ° | 2.7 m | Limit not yet confirmed | Within the guidance | Advisory |
| 16 | 162.5 mm | 181 mm | 506 mm | 41.9 ° | 2.71 m | Limit not yet confirmed | Within the guidance | Advisory |
| 17 | 152.9 mm | 170 mm | 475.9 mm | 42 ° | 2.72 m | Limit not yet confirmed | Within the guidance | Advisory |
Marking out the string (from the bottom, along the floor and up)
- Riser 1: top at 216.7 mm up, 0 mm along
- Riser 2: top at 433.3 mm up, 241 mm along
- Riser 3: top at 650 mm up, 482 mm along
- Riser 4: top at 866.7 mm up, 723 mm along
- Riser 5: top at 1,083.3 mm up, 964 mm along
- Riser 6: top at 1,300 mm up, 1,205 mm along
- Riser 7: top at 1,516.7 mm up, 1,446 mm along
- Riser 8: top at 1,733.3 mm up, 1,687 mm along
- Riser 9: top at 1,950 mm up, 1,928 mm along
- Riser 10: top at 2,166.7 mm up, 2,169 mm along
- Riser 11: top at 2,383.3 mm up, 2,410 mm along
- Riser 12: top at 2,600 mm up, 2,651 mm along
Show the working
- Riser counts compared: 12 to 17 (your range)
- 12 risers: 2,600 ÷ 12 = 216.7 mm rise; going 241 mm; 2R + G = 2 × 216.7 + 241 = 674.3 mm; pitch 42°
- 13 risers: 2,600 ÷ 13 = 200 mm rise; going 223 mm; 2R + G = 2 × 200 + 223 = 623 mm; pitch 41.9°
- 14 risers: 2,600 ÷ 14 = 185.7 mm rise; going 207 mm; 2R + G = 2 × 185.7 + 207 = 578.4 mm; pitch 41.9°
- 15 risers: 2,600 ÷ 15 = 173.3 mm rise; going 193 mm; 2R + G = 2 × 173.3 + 193 = 539.7 mm; pitch 41.9°
- 16 risers: 2,600 ÷ 16 = 162.5 mm rise; going 181 mm; 2R + G = 2 × 162.5 + 181 = 506 mm; pitch 41.9°
- 17 risers: 2,600 ÷ 17 = 152.9 mm rise; going 170 mm; 2R + G = 2 × 152.9 + 170 = 475.9 mm; pitch 42°
- Going for a 42° pitch: rise ÷ tan 42°, rounded up to the mm
- Suggested: 12 risers, total going 11 × 241 mm = 2,651 mm
How it works
- Rise = total rise ÷ number of risers (n); treads = n − 1
- Going = the larger of the Table 1.1 minimum going and rise ÷ tan(maximum pitch), rounded up to the next mm (or your going, if you enter one)
- 2R + G = 2 × rise + going; pitch = arctan(rise ÷ going); total going = treads × going
- Riser counts compared: from total rise ÷ maximum rise (rounded up) to total rise ÷ minimum rise (rounded down)
- Suggested option: the fewest risers with nothing outside the guidance, 2R + G in the normal range and a flight that fits the space
2R + G between 550 and 700 mm is described as the normal relationship in Approved Document K, so it's shown as Advisory, not a pass or fail.
Measure the total rise between finished floor levels (after flooring and screed), not between joists.
Our default (adjustable)
These are typical planning figures and our own allowances, not facts about your product. Change any of them in the calculator to match your bag, pack or tin.
| Figure | Our default (adjustable) | Kind | Source |
|---|---|---|---|
| Headroom guidance | 2 m | Regulation or HSE figure Approved Document K 2013, headroom (loft conversions differ) Not yet checked against the source | gov.uk (checked 19 October 2026) brief v2 C1 (headroom 2.0 m). Researcher to cite the paragraph and the loft-conversion figure. |
Regulations and standards
- Approved Document K 2013, Table 1.1 (rise, going and pitch)
- Approved Document K 2013, para 1.3
- Approved Document K 2013, headroom
Explained: Approved Document K (stairs and guarding).
The checks use Approved Document K for England. Wales has its own Approved Document K; Scotland's Technical Handbook sets different figures (for example the minimum going); Northern Ireland has its own Technical Booklet.
| Table | Clause | Nations | Status |
|---|---|---|---|
| Stair rise, going, pitch and 2R+G limits | Approved Document K 2013, Table 1.1 and para 1.3 | England | 7/21 values entered Not yet checked against the source |