Wheelchair Ramp Slope Calculator
Ramp length for a given rise, the landings the run forces on you, and the total footprint once they are included. ADA slope by default.
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Results
Side elevation, drawn to scale. The bar shows the straight run you said was available.
Working
- run = rise 24 in x 12 = 288 in
- slope = 1 / 12 = 8.3%, angle = atan(1/12) = 4.8 degrees
- ramp length = sqrt(288^2 + 24^2) = 289 in
- sections = ceil(24 / 30 in max rise per run) = 1
- landings = 0 intermediate + 2 at the ends = 2
- footprint = 288 + 2 x 60 = 408 in
Quick answer
ADA sets the maximum ramp slope at 1:12, so every inch of rise needs a foot of run. A 24 in rise needs 24 ft of ramp. What catches people out is that no single run may rise more than 30 in before a level landing, and landings are 5 ft each, so the total footprint is always longer than the ramp itself.
run ft = rise in; ramp length = sqrt(run^2 + rise^2); footprint = run + landings x 60 in
Worked example
A 24 in rise from a path to a front door, ADA slope, with 24 ft of straight run available.
Working
- run = rise 24 in x 12 = 288 in
- slope = 1 / 12 = 8.3%, angle = atan(1/12) = 4.8 degrees
- ramp length = sqrt(288^2 + 24^2) = 289 in
- sections = ceil(24 / 30 in max rise per run) = 1
- landings = 0 intermediate + 2 at the ends = 2
- footprint = 288 + 2 x 60 = 408 in
The ramp itself is 24 ft, which fits the space exactly, and that is the trap. Add the two 5 ft landings and the assembly needs 34 ft, so this rise does not fit in a straight line here and has to turn.
Ramp length by rise at ADA 1:12
At 1:12 the run in feet equals the rise in inches. Footprint assumes a landing top and bottom plus any the rise forces in between.
| Rise | Horizontal run | Ramp length | Mid landings | Total footprint |
|---|---|---|---|---|
| 3 in | 3 ft | 3 ft | 0 | 13 ft |
| 6 in | 6 ft | 6 ft | 0 | 16 ft |
| 12 in | 12 ft | 12 ft 0.5 in | 0 | 22 ft |
| 18 in | 18 ft | 18 ft 0.5 in | 0 | 28 ft |
| 24 in | 24 ft | 24 ft 1 in | 0 | 34 ft |
| 30 in | 30 ft | 30 ft 1 in | 0 | 40 ft |
| 36 in | 36 ft | 36 ft 1.5 in | 1 | 51 ft |
| 48 in | 48 ft | 48 ft 2 in | 1 | 63 ft |
A rise over 30 in cannot be done in one run. Above about 30 in, a switchback with a 60 by 60 in turning landing is usually the only thing that fits a domestic plot.
At a glance
| What it does | Ramp length, landings, handrail trigger and total footprint for a given rise |
|---|---|
| Inputs needed | Total rise, who uses it, straight run available, clear width |
| Main output | Ramp length and total footprint |
| Formula | run = rise x 12 at 1:12; footprint = run + landings x 60 in |
| Category | Accessibility |
| Cost | Free, no sign-up, no download |
How to use the Wheelchair Ramp Slope Calculator
- Measure the total rise from the finished ground to the finished floor inside the door, not to the top step.
- Leave the slope at ADA unless the ramp is private and someone else is always pushing.
- Enter the straight run you genuinely have, stopping at the first wall, path or boundary.
- Check the footprint, not the ramp length. The landings are what usually decide whether it fits.
- If it does not fit straight, plan a switchback with a 60 by 60 in level turning landing.
Frequently asked questions
What is the maximum slope for a wheelchair ramp?
1:12 under the ADA, which is one inch of rise per twelve inches of run, or 8.3 per cent. Steeper ratios are sold for portable ramps and assisted use, but they are manufacturer guidance rather than a standard, and 1:12 is what anyone propelling themselves needs.
How long does a ramp need to be for 2 feet of rise?
Twenty four feet of ramp at 1:12, plus landings. With a five foot landing top and bottom the assembly needs thirty four feet, which is more than most front gardens allow in a straight line.
When does a wheelchair ramp need a landing?
At the top and bottom always, and part way whenever a single run would rise more than 30 in. Landings must be at least 60 in long, as wide as the ramp, and level in both directions.
Do wheelchair ramps need handrails?
Once the rise is over 6 in or the run over 72 in. They go on both sides, with the gripping surface 34 to 38 in above the ramp, running continuously and extending 12 in level past the top and bottom.
How wide should a wheelchair ramp be?
36 in clear between the handrails is the minimum. That is clear width, so a frame with rails mounted inboard needs to be wider overall than 36 in.
What if the ramp will not fit in a straight line?
Turn it. A switchback with a 60 by 60 in level landing at the turn halves the length in each direction. Where even that fails, a vertical platform lift is usually the alternative rather than a steeper ramp.
Slope, landing and handrail figures follow the ADA Standards for Accessible Design, section 405. Local building codes and, outside the United States, national accessibility standards may be stricter. This tool sizes a ramp; it is not a substitute for a permit review or, where the ramp is a means of egress, for sign-off by your building department.
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