Ramp Calculator – Length, Angle & Volume
Calculate ramp length, angle, surface area, and concrete volume for any slope ratio. Supports ADA 1:12, residential, and custom slope ratios.
Ramp Calculator Formula
Ramp Length = Rise ÷ Slope Ratio × Slope Ratio; Angle = atan(Rise / Length)
How to Calculate Ramp
- 1. Convert rise to feet if given in inches: Rise (ft) = Rise (in) ÷ 12
- 2. Calculate ramp length: Length (ft) = Rise (ft) × Slope Ratio
- 3. Calculate angle: Angle = atan(Rise / Length) × (180/π)
- 4. Calculate surface area: Area = Length × Width (if width provided)
- 5. Calculate volume: Volume = (Length × Width × Rise) / 2 (triangular prism)
Example Calculation
Let's say you're building an ADA-compliant ramp for a 24-inch rise with 5ft width.
- rise: 24
- slopeRatio: 12
- width: 5
Ramp length = 24 ft, angle = 4.8°, surface area = 120 sq ft, volume = 50.0 ft³
Tips
- ADA requires a maximum 1:12 slope ratio (1 foot of rise per 12 feet of run) for wheelchair ramps
- For every 30 feet of ramp length, ADA requires a 5-foot level landing
- Residential ramps can use steeper slopes (1:8 to 1:10) but 1:12 is the safest
- Add 5–10% extra concrete for waste when ordering for ramp construction
Frequently Asked Questions
What is the standard slope for a wheelchair ramp?
The ADA standard is a 1:12 slope ratio, meaning for every 1 inch of rise you need 12 inches (1 foot) of ramp length. For example, a 24-inch rise requires a 24-foot long ramp.
How do you calculate the volume of a ramp?
The volume of a triangular ramp is calculated as: Volume = (Length × Width × Rise) / 2. This is because the cross-section is a triangle. Measure all dimensions in the same unit (feet).
What is the maximum slope for a ramp?
ADA maximum is 1:12 (4.8°) for wheelchair access. For general pedestrian use, a maximum of 1:8 (7.1°) is acceptable. For vehicle ramps, slopes up to 1:5 (11.3°) may be used. Steeper slopes require handrails.
How long should a ramp be for 3 steps?
Three standard steps have a total rise of about 21–24 inches. At a 1:12 ADA slope, you need 21–24 feet of ramp length. At a steeper 1:8 slope, you need 14–16 feet.