Use this wheelchair ramp slope calculator to measure the appropriate length and angle of a ramp for safe and comfortable handicap ramp access.
A building entrance with a 30-inch height difference from ground level. A handicap ramp slope / length calculator might suggest a ramp length of 30 feet to achieve a 1:12 slope ratio, which is generally considered the gold standard for wheelchair accessibility.
Wheelchair Ramp Slope Calculator
| Rise (inches) | Slope Ratio | Ramp Length (inches) | Ramp Length (feet) |
|---|---|---|---|
| 12 | 1:12 | 12 | 1 |
| 12 | 1:10 | 10 | 0.83 |
| 12 | 1:8 | 9 | 0.75 |
| 24 | 1:12 | 24 | 2 |
| 24 | 1:10 | 20 | 1.67 |
| 24 | 1:8 | 18 | 1.5 |
| 36 | 1:12 | 36 | 3 |
| 36 | 1:10 | 30 | 2.5 |
| 36 | 1:8 | 27 | 2.25 |
| 48 | 1:12 | 48 | 4 |
| 48 | 1:10 | 40 | 3.33 |
| 48 | 1:8 | 36 | 3 |
| 60 | 1:12 | 60 | 5 |
| 60 | 1:10 | 50 | 4.17 |
| 60 | 1:8 | 45 | 3.75 |
| 72 | 1:12 | 72 | 6 |
| 72 | 1:10 | 60 | 5 |
| 72 | 1:8 | 54 | 4.5 |
| 84 | 1:12 | 84 | 7 |
| 84 | 1:10 | 70 | 5.83 |
| 84 | 1:8 | 63 | 5.25 |
| 96 | 1:12 | 96 | 8 |
| 96 | 1:10 | 80 | 6.67 |
| 96 | 1:8 | 72 | 6 |
Wheelchair Ramp Slope Formula
The formula for calculating wheelchair ramp slope is:
Slope Ratio = Rise : RunWhere:
- Rise is the vertical height difference
- Run is the horizontal length of the ramp
This ratio is typically expressed as 1:X, where X represents the horizontal distance required for every 1 unit of vertical rise. For instance, a slope of 1:12 means that for every 1 inch of rise, the ramp extends 12 inches horizontally.
To calculate the required ramp length, use this formula:
Ramp Length = Rise × Slope RatioFor example, if you have a 24-inch rise and want a 1:12 slope: Ramp Length = 24 inches × 12 = 288 inches (24 feet)
How Long Should a Ramp Be for 24 Inches?
Using the ADA-recommended 1:12 slope:
- 1:10 slope: 24 inches × 10 = 240 inches (20 feet)
- 1:8 slope: 24 inches × 8 = 192 inches (16 feet)
For a 24-inch rise, the ideal ramp length depends on the desired slope ratio.
Ramp Length = 24 inches × 12 = 288 inches (24 feet)How Long Should a Ramp Be for a 3-Foot Rise?
Using the preferred 1:12 slope:
- 1:10 slope: 36 inches × 10 = 360 inches (30 feet)
- 1:8 slope: 36 inches × 8 = 288 inches (24 feet)
A 3-foot (36-inch) rise requires careful consideration to ensure accessibility.
Ramp Length = 36 inches × 12 = 432 inches (36 feet)What is the Proper Slope for a Wheelchair Ramp?
The widely accepted standard is a 1:12 slope ratio.
This 1:12 ratio strikes a balance between accessibility and practicality:
- It’s gentle enough for most wheelchair users to navigate independently
- It minimizes the risk of tipping or losing control
- It complies with ADA (Americans with Disabilities Act) guidelines for public buildings
In some cases, slightly steeper slopes may be permissible:
- 1:10 for short ramps (up to 6 inches of rise)
- 1:8 for very short ramps (up to 3 inches of rise) in residential settings
How Long Should a Ramp Be for 4 Steps?
Assuming standard step heights of 7 inches:
- 1:10 slope: 28 inches × 10 = 280 inches (23.33 feet)
- 1:8 slope: 28 inches × 8 = 224 inches (18.67 feet)
To determine the appropriate ramp length for 4 steps, we first need to calculate the total rise.
Total Rise = 4 steps × 7 inches = 28 inchesNow, applying the recommended 1:12 slope ratio:
Ramp Length = 28 inches × 12 = 336 inches (28 feet)
References
- ADA.gov – 2010 ADA Standards for Accessible Design: https://www.ada.gov/2010ADAstandards_index.htm
- U.S. Access Board – Ramps and Curb Ramps: https://www.access-board.gov/ada/guides/chapter-4-ramps-and-curb-ramps/
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