Ramp gradient calculator: length, slope and Part M check
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 |
|---|---|
| What do you know? | The gradient I want |
| Rise | 300 mm |
| Gradient: 1 in | 15 |
| Building | A home |
Going: 4.50 m at 1:15
- Limit not yet confirmed Gradient no steeper than the steepest in the table (n in 1:n): 15 The limit for this check hasn't been confirmed yet: check the source. England: Approved Document M, ramped access (gradient against going of a flight). Check with the source
- Limit not yet confirmed Going of one flight against the longest allowed at this gradient: 4.5 m The Approved Document M figure for this gradient hasn't been confirmed yet (or the gradient is outside the table): check the source. England: Approved Document M, ramped access (gradient against going of a flight). Check with the source
| Result | Value |
|---|---|
| Going (plan length of the slope) | 4.5 m |
| Gradient | 1:15 |
| As a percentage | 6.67% |
| In degrees | 3.81 ° |
| Length along the slope | 4.51 m |
Show the working
- Going: 300 mm × 15 = 4.5 m
- 1:15 = 6.67% = 3.81°; along the slope √(0.3² + 4.5²) = 4.51 m
How it works
- Gradient 1:n means 1 unit of rise for every n units of going (on plan)
- Going = rise × n; or, from the length available, n = going ÷ rise
- Percentage = 100 ÷ n; degrees = arctan(1 ÷ n); length along the slope = √(rise² + going²)
- Approved Document M allows steeper gradients only on shorter flights: the longest flight for your gradient is read from the table (between rows, interpolated)
- Flights = going ÷ longest flight, rounded up; landings = flights + 1
Approved Document M also sets ramp widths, landing lengths and handrails: check the full guidance or ask building control.
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.
This calculator has no built-in defaults: every figure comes from you or your product's data.
Regulations and standards
- Approved Document M (ramped access: gradient against the going of a flight)
Explained: Approved Document M (access).
The check uses Approved Document M for England. Wales has its own Approved Document M; Scotland and Northern Ireland have their own guidance.
| Table | Clause | Nations | Status |
|---|---|---|---|
| Ramp gradient against the longest going of a flight | Approved Document M (ramped access: gradient and going of a flight; Researcher to cite the table per volume) | England | 0/6 values entered Not yet checked against the source |