ADA Ramp Slope Calculator
Find the ramp length you need for a given rise at an ADA-compliant slope, plus the slope percent and required landings.
What your result means
Ramp run length is the horizontal distance the ramp covers at your chosen slope. Slope is that expressed as a percent (1:12 equals 8.3%, the ADA maximum). Landings needed reflects the ADA rule of a level rest platform for every 30 inches of rise. Gentler slopes are easier to use but need more room. For a stair alternative, see our stair calculator.
How to use this calculator
- Measure the total rise the ramp must climb, in inches.
- Pick a slope ratio — 1:12 is the ADA maximum; gentler is better.
- Read the required run length, slope percent, and landings.
- Add a 5-foot level landing at the top and bottom, plus any mid-runs.
- Confirm width, handrail, and edge-protection rules in the ADA guidelines.
The formula
At a 1:12 ratio every inch of rise needs 12 inches of run, which is an 8.3% slope — the ADA maximum. ADA also requires a level landing for each 30 inches of vertical rise.
Worked example
A 24-inch rise at the 1:12 ADA maximum needs 24 × 12 = 288 inches of run, or 24 feet, at an 8.3% slope. Because the rise is under 30 inches, no intermediate landing is required — just the top and bottom platforms.
ADA ramp requirements
| Requirement | ADA standard |
|---|---|
| Max slope | 1:12 (8.3%) |
| Max rise per run | 30 in, then a landing |
| Min clear width | 36 in |
| Landing size | 60 × 60 in min |
| Handrails | Both sides if rise > 6 in |
Tips & gotchas
- 1:12 is the steepest ADA allows — a gentler 1:16 or 1:20 is easier and safer.
- Every 30 inches of rise needs a level landing to rest and turn.
- Top and bottom landings must be at least 60 inches long and level.
- Handrails are required on both sides when the rise exceeds 6 inches.
- These are planning figures — follow the full ADA Standards for a compliant ramp.
Frequently asked questions
What is the ADA maximum ramp slope?
1:12, meaning 12 inches of run for every inch of rise — an 8.3% grade. Gentler slopes like 1:16 or 1:20 are more comfortable.
How long should a wheelchair ramp be?
At the 1:12 maximum, the run is 12 times the rise. A 24-inch rise needs a 24-foot ramp run, plus level landings.
When does a ramp need a landing?
ADA requires a level landing for every 30 inches of vertical rise, and level landings at the top and bottom of every ramp.
How wide must an ADA ramp be?
At least 36 inches of clear width between handrails, with 60-by-60-inch landings for turning.
Do I always need handrails?
ADA requires handrails on both sides when the ramp rise is greater than 6 inches or the run is longer than 72 inches.
Related calculators
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