Ramp Calculator
How long a ramp needs to be for a given rise: ADA 1:12, England's Approved Document M, Australian rules or your own gradient, with landings.
A ramp's length is its rise times its gradient: at 1:12, every inch of rise needs 12 inches of ramp. For a 24 in rise that's 24 ft of ramp, plus a 5 ft landing at the top and bottom, so 34 ft in a straight line. The rules decide the gradient. In the US, the ADA allows 1:12 at most and a 30 in rise per run. England's Approved Document M allows 1:12 only for short ramps, getting gentler to 1:20 for a 10 m going, with no more than 500 mm of rise per flight. Australia's NCC allows ramps in houses up to 1:8, while accessible ramps must be much gentler. Choose the rules and enter the rise, and the calculator gives the ramp length, runs or flights, landings and slope.
- Ramp length
- 24 ft
- With landings
- 34 ft
- Runs
- 1
- Slope
- 4.76°
horizontal, at 1:12
2 landings
24 in rise each
8.3% · surface 24.08 ft
How it was worked out
- ADA ramps are no steeper than 1:12 and rise no more than 30 in per run: 24 in ÷ 30 in → 1 run
- Landings: 2 × 5 ft (top, bottom) = 10 ft
- Total length on a straight line: 24 ft of ramp + 10 ft of landings = 34 ft
Common use cases
- Plan a wheelchair ramp to a front door
- Size a ramp for a shed, garage or trailer
- Check a ramp against ADA or Part M limits
- Work out how much space a ramp needs before building
How to use
- Choose the rules: ADA, Approved Document M, Australian housing, or your own gradient.
- Enter the total rise from the ground to the top landing.
- Read the ramp length, the number of runs or flights, the landings and the total length.
- Check the notes for the width and handrail rules that also apply.
FAQ
How long does a ramp need to be?
Multiply the rise by the gradient. At the ADA's 1:12, a 24 in rise needs 24 ft of ramp; at 1:20, 40 ft. Add landings: the ADA asks for landings at least 60 in long at the top and bottom of each run.
What is the ADA ramp slope?
No steeper than 1:12 (8.33%), with no more than 30 in of rise in any one run, at least 36 in clear width between handrails, and handrails on both sides when the rise is over 6 in.
What gradient does Approved Document M allow?
1:12 for a going of up to 2 m, getting gentler by one step per metre to 1:20 for a 10 m going, with a maximum rise of 500 mm per flight, at least 1.5 m width and 1.2 m landings at the foot and head.
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Results are estimates for planning and buying materials, worked out from the figures you enter and typical values (weights, coverage, sizes) that vary by product and supplier. They are not engineering, building or professional advice. Check your local building code, the product maker's instructions and your supplier's figures before you buy or build, and use a qualified professional for structural, electrical and gas work. The code checks cover the main dimensions only; the rules where you live, and your building inspector, have the final say.