Ramp Calculator
Find the ramp length and slope needed for a given height — for wheelchairs, vehicles or loading bays.
Inputs
Formula
- Ramp length = rise × slope ratio
- Slope % = rise ÷ length × 100
- Angle = arctan(rise ÷ length)
A ramp is defined by its slope ratio: 1:12 means 12 units of run for every 1 unit of rise, the accessibility standard for wheelchairs. Vehicle ramps can be steeper (1:8), but anything above 1:6 will scrape a car's underbody. Landings are needed every 750 mm of rise on an accessible ramp.
Step-by-step calculation
- 1
Length
rise × 12
36 ft
- 2
Slope
1 ÷ ratio
8.33%
- 3
Angle
arctan(1/ratio)
4.76°
Worked example
- 1A 3 ft rise at the 1:12 wheelchair standard needs 36 ft of ramp.
- 2Slope = 3 ÷ 36 = 8.33%, an angle of 4.8°.
- 3With a 2.5 ft rise between landings, one intermediate landing is required.
Tips
- Provide a level landing of at least 1.5 m at the top and bottom.
- Use a broom or grooved finish on concrete ramps — smooth ramps are dangerous when wet.
Frequently asked questions
What slope is required for a wheelchair ramp?
1:12 (8.33%) is the accessibility standard, with landings every 750 mm of rise.
How steep can a car ramp be?
1:8 is comfortable, 1:6 is the practical maximum with transition curves at both ends.
How long is a ramp for 2 feet?
24 ft at the 1:12 wheelchair standard, or 16 ft for a vehicle ramp at 1:8.
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