1. What is a Ramp Slope Ratio Calculator?

Definition: This calculator determines the slope ratio (1:R) of a ramp based on its length and vertical height.

Purpose: It helps architects, builders, and accessibility planners design ramps with proper slope ratios for safety and compliance.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( R \) — Slope ratio (unitless, expressed as 1:R)
• \( L \) — Ramp length (feet)
• \( H \) — Ramp height/rise (feet)

Explanation: The ratio represents how many units of length are needed for each unit of height (e.g., 1:12 means 12 feet of length for 1 foot of rise).

3. Importance of Ramp Slope Calculation

Details: Proper slope ratios ensure accessibility compliance (ADA recommends 1:12 for wheelchair ramps), safety, and usability.

4. Using the Calculator

Tips: Enter the ramp length and height in feet. Both values must be > 0. The result shows the ratio in 1:R format.

5. Frequently Asked Questions (FAQ)

Q1: What's the standard slope ratio for wheelchair ramps?
A: ADA recommends 1:12 (1 inch rise per 12 inches of run), with 1:16 being more comfortable for manual wheelchairs.

Q2: How does slope ratio relate to angle?
A: The angle θ = arctan(H/L). A 1:12 ratio equals about 4.76° slope.

Q3: What's the maximum allowed slope for accessibility?
A: ADA maximum is 1:12 for ramps up to 30 inches high. Steeper slopes may be allowed for existing constraints (max 1:8).

Q4: When would I use a different ratio?
A: Vehicle ramps (1:4 to 1:6), loading docks (1:10), or residential ramps where space is limited (but steeper than 1:12 isn't ADA compliant).

Q5: How do I convert ratio to percentage grade?
A: Percentage grade = (H/L) × 100. A 1:12 ratio equals 8.33% grade.