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Construction & HomestructuralUnited States only

Ramp Slope Calculator

Ramp length for a given rise and slope. Accessibility standards cap the rise per flight, so a tall rise needs intermediate landings that add substantially to the total length.

Also called: wheelchair ramp calculator, accessibility ramp.

Ramp length needed (mm)
7,200

7,200mm of ramp for a 600mm rise at 1 in 12, which is 4.76 degrees. The rise is within a single flight, so no intermediate landing is required.

Angle (degrees)
4.76
Slope as a percentage
8.33%
Intermediate landings needed
0
Total length including landings (mm)
7,200
On landings
The rise is within a single flight, so no intermediate landing is required.
How this is calculated
Method and background

How this is calculated

A 1 in 12 slope needs twelve units of run for every unit of rise, which is why a modest step becomes a long ramp. Most accessibility standards also cap the rise of a single flight at around 750mm, requiring a level landing before continuing, and those landings add roughly 1.5 metres each. The total including landings is usually what determines whether a ramp fits at all.

ramp run = rise * the slope denominator
r
Rise (mm)
n
Slope denominator, as in 1 in n

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

a 600mm rise at 1 in 12

Rise (mm)
600
Slope, 1 in
12

Ramp length needed (mm)7,200

600 * 12, worked by hand

Open this example

a tall rise needs landings

Rise (mm)
1,500
Slope, 1 in
12

Ramp length needed (mm)18,000

boundary: 18000 of ramp plus one landing

Open this example

Method and limits

What it assumes

  • A straight ramp with 1500mm landings.

What it deliberately does not model

  • Standards differ: 1 in 12 is common, but 1 in 15 or 1 in 20 is required for longer runs in several codes.
  • Handrails, edge protection and surface finish are separate requirements.

Formula version 1.0.0 · definition 1.0.0 · United States · Report a problem with this calculator

Frequently asked questions

Why is 1 in 12 so long?
Because it is set by what a person can self-propel in a wheelchair, not by what fits. A 600mm rise needs 7.2 metres of ramp, which is why ramps so often need to switchback.