For ADA compliance, the most common ratio is 1:12 (1 inch rise for every 12 inches of run). Other steeper slopes may be permitted for very short ramps.
Understanding ADA Wheelchair Ramp Requirements
Wheelchair ramps are essential for providing accessible pathways for individuals with mobility impairments, ensuring compliance with the Americans with Disabilities Act (ADA). The ADA sets specific standards for ramp construction to guarantee safety and usability.
Key ADA Ramp Specifications:
Slope: The maximum slope for a wheelchair ramp is 1:12. This means for every 1 inch of vertical rise, there must be at least 12 inches of horizontal run. Steeper slopes (up to 1:8) are permissible for very short ramps (less than 6 inches rise).
Landings: Landings are required at the top and bottom of the ramp, and at any point where the ramp changes direction. Landings must be level and at least 60 inches by 60 inches (5 feet by 5 feet) if the ramp runs straight. If the ramp turns 90 degrees, the landing must be at least 60 inches by 72 inches (5 feet by 6 feet).
Width: The clear width of the ramp must be at least 36 inches (3 feet) between handrails.
Handrails: Handrails are required on both sides of ramps with a rise greater than 6 inches or a run greater than 72 inches. They must be between 34 and 38 inches high and extend 12 inches beyond the top and bottom of the ramp.
Edge Protection: Ramps should have edge protection (like a curb or barrier) to prevent wheels from slipping off.
How the ADA Wheelchair Ramp Calculator Works:
This calculator helps you determine the minimum required horizontal length (run) for a wheelchair ramp based on the total vertical height (rise) you need to overcome and the desired slope ratio.
The core principle is based on the slope ratio. The ADA mandates a maximum slope of 1:12. This means:
Required Run = Total Rise × Slope Denominator
For example, if you have a total rise of 24 inches and are using the standard 1:12 slope ratio:
Required Run = 24 inches × 12 = 288 inches
This calculator takes your input for 'Total Rise' and the 'Desired Max Slope Ratio' (you typically enter the denominator, like '12' for 1:12) and computes the minimum horizontal length needed. It also provides a check against the maximum permitted slope to alert you if your chosen ratio is too steep for the given rise.
When to Use This Calculator:
Planning new construction or renovations.
Assessing existing structures for ADA compliance.
Estimating the space needed for a wheelchair ramp.
Ensuring accessibility in public and private spaces.
Remember that this calculator provides essential dimensional guidance. Always consult local building codes and ADA guidelines, and consider consulting with accessibility professionals for comprehensive compliance.
This calculator is for informational purposes only and does not constitute professional advice. Always verify calculations and consult with qualified professionals and local authorities for compliance with building codes and accessibility standards.
function calculateRamp() {
var rise = parseFloat(document.getElementById("rise").value);
var runInput = document.getElementById("run").value;
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous results
if (isNaN(rise) || rise <= 0) {
resultDiv.innerHTML = "Please enter a valid positive number for the Total Rise.";
resultDiv.style.backgroundColor = "#dc3545"; // Error red
return;
}
var slopeDenominator;
if (runInput.includes(':')) {
var parts = runInput.split(':');
if (parts.length === 2) {
slopeDenominator = parseFloat(parts[1]);
} else {
resultDiv.innerHTML = "Please enter the slope ratio in the format '1:12' or just the denominator like '12'.";
resultDiv.style.backgroundColor = "#dc3545";
return;
}
} else {
slopeDenominator = parseFloat(runInput);
}
if (isNaN(slopeDenominator) || slopeDenominator <= 0) {
resultDiv.innerHTML = "Please enter a valid positive number for the Slope Ratio Denominator (e.g., 12).";
resultDiv.style.backgroundColor = "#dc3545";
return;
}
var requiredRun = rise * slopeDenominator;
var requiredRunInFeet = requiredRun / 12;
var complianceMessage = "";
var outputColor = "#28a745"; // Success green
// ADA maximum slope checks
if (rise <= 6 && slopeDenominator < 8) {
complianceMessage = "Note: While compliant with the steepness for short ramps (max 1:8 for rise 12) {
complianceMessage = "Warning: The selected slope is steeper than the standard ADA maximum of 1:12. This may not be compliant for longer ramps.";
outputColor = "#ffc107"; // Warning yellow
}
resultDiv.innerHTML = "Required Horizontal Run: " + requiredRun.toFixed(2) + " inches(" + requiredRunInFeet.toFixed(2) + " feet)";
if (complianceMessage) {
resultDiv.innerHTML += "" + complianceMessage + "";
}
resultDiv.style.backgroundColor = outputColor;
}