Wheelchair Ramp Slope Calculator
Calculate the horizontal run, sloped ramp length, and slope percentage for an accessible ramp, and verify ADA compliance.
in
Rise unit
Target slope ratio
About 24.08 ft — meets ADA slope
- 1
Horizontal run
24 × 12 = 288 - 2
Ramp length (hypotenuse)
√(24² + 288²) = 289Sloped surface length — hypotenuse of the rise-and-run right triangle.
How does this calculator work?
For a wheelchair ramp, multiply the vertical rise by the slope ratio to get the horizontal run (1:12 means 1 ft of run per inch of rise). The sloped length is √(rise² + run²). Keep slope at or below 8.33% to meet ADA, and add a landing every 30 ft of run.
Formula
How this is calculated
Enter the vertical rise (the total height the ramp must climb) in inches or centimeters, and choose a target slope ratio. A ratio of 1:N means the ramp travels N units horizontally for every 1 unit it rises, so the horizontal run equals rise × N. The slope as a percentage is simply 100 / N, which makes the 1:12 ADA maximum equal to 8.33%; gentler ratios such as 1:16 (6.25%) or 1:20 (5%) are easier to climb and 1:20 needs no handrails.
The sloped ramp length is the hypotenuse of the rise-and-run right triangle, length = √(rise² + run²), which is the actual surface you walk or roll on. Because run is much larger than rise on a compliant ramp, the length is only slightly longer than the run. The RangeMeter compares your computed slope against the 8.33% ADA limit so steeper-than-allowed designs are flagged.
The ADA also requires a level landing (typically 60 in / 1.5 m long) at the top and bottom and after every 30 ft (about 9 m) of horizontal run; the calculator estimates how many intermediate landings are needed. Results assume a straight single-pitch ramp and ignore landing length, thresholds, and handrail extensions, so add those when laying out the real installation. All length outputs share the unit of the rise, with a feet/metre conversion shown for convenience.
Frequently asked questions
The ADA sets a maximum running slope of 1:12, or 8.33% (about 4.76°). Choosing a gentler ratio such as 1:16 or 1:20 reduces effort and improves safety, especially for unassisted users.
At the 1:12 ADA ratio the horizontal run in feet equals the rise in inches — a 24 in rise needs a 24 ft run. The actual ramp surface (the hypotenuse) is only marginally longer than that run.
ADA guidelines call for a level landing at the top and bottom of every ramp and after each 30 ft (roughly 9 m) of continuous run, plus wherever the ramp changes direction.
Also known as
TG we-Calculate Editorial Team. (2026). Wheelchair Ramp Slope Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/wheelchair-ramp-calculator
TG we-Calculate Editorial Team. "Wheelchair Ramp Slope Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/wheelchair-ramp-calculator.
TG we-Calculate Editorial Team, "Wheelchair Ramp Slope Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/wheelchair-ramp-calculator
@misc{wecalculate_wheelchair_ramp_calculator, title = {Wheelchair Ramp Slope Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/wheelchair-ramp-calculator}}, year = {2026}, note = {TG we-Calculate} }
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