Wheelchair Ramp Slope Calculator

Last updated: 21 Oct 2025 | Author: Brij | Review By: Irshad

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This calculator helps you determine the slope and length of a wheelchair ramp. Simply enter the Rise (vertical height) and Run (horizontal length) of the ramp

Rise: The vertical height of the ramp:

Run: The horizontal length of the ramp:

Result

Slope Length:

Slope Angle:

Degree

Common Ramp Rise vs. Run Table (ADA Recommendations)

Rise (inches)	Recommended Run (inches)	Slope Ratio	Angle (°)
1	12	1:12	4.76°
2	24	1:12	4.76°
3	36	1:12	4.76°
4	48	1:12	4.76°
6	72	1:12	4.76°
12	144	1:12	4.76°

Building a wheelchair ramp requires careful slope calculation to ensure accessibility and safety. This Wheelchair Ramp Slope Calculator helps you find the correct ramp length and slope angle by simply entering the rise (height) and run (horizontal length).

What is a Wheelchair Ramp Slope?

The wheelchair ramp slope is the incline of the ramp — how steep or gentle it is. It’s the ratio between the vertical rise and the horizontal run.

A gentle slope provides easier access for wheelchair users.
A steeper slope requires more effort and may not meet accessibility codes (like ADA guidelines).

Formula to Calculate Slope Length

To find the ramp slope length, use the Pythagorean theorem:

$\text{Slope Length} = \sqrt{(\text{Rise}^2 + \text{Run}^2)}$

Formula to Calculate Slope Angle

To find the slope angle (in degrees), use trigonometry:

$\text{Slope Angle} = \tan^{-1}\left(\frac{\text{Rise}}{\text{Run}}\right)$

Formula to Calculate Slope Ratio

The slope ratio expresses how much the ramp rises per horizontal distance.

$\text{Slope Ratio} = 1 : \left(\frac{\text{Run}}{\text{Rise}}\right)$

Example Calculations

Example 1

If:

Rise = 1 ft
Run = 12 ft

Then:

$\text{Slope Length} = \sqrt{(1^2 + 12^2)} = 12.04 \, \text{ft}$

$\text{Slope Angle} = \tan^{-1}\left(\frac{1}{12}\right) = 4.76^\circ$

Example 2

If:

Rise = 2 ft
Run = 24 ft

$\text{Slope Length} = \sqrt{(2^2 + 24^2)} = 24.08 \, \text{ft}$

$\text{Slope Angle} = \tan^{-1}\left(\frac{2}{24}\right) = 4.76^\circ$

Example 3

If:

Rise = 3 ft
Run = 20 ft

$\text{Slope Length} = \sqrt{(3^2 + 20^2)} = 20.22 \, \text{ft}$

$\text{Slope Angle} = \tan^{-1}\left(\frac{3}{20}\right) = 8.53^\circ$

Example Summary

Let’s take a real example:

If your porch height (rise) is 18 inches, then following the 1:12 slope rule:

FAQs

1. What is the ideal slope for a wheelchair ramp?

The ADA recommends a 1:12 slope, meaning 1 inch of rise for every 12 inches (1 foot) of run.

2. How do I calculate ramp length for a given height?

Use the Pythagorean formula:

$\text{Length} = \sqrt{(\text{Rise}^2 + \text{Run}^2)}$

3. Can I make the ramp steeper to save space?

Technically yes, but it becomes harder to use and may not meet ADA compliance. For short ramps (like portable ones), a 1:10 slope can work temporarily.

4. What’s the maximum allowable slope for wheelchair ramps?

According to ADA standards, the maximum slope is 1:12 (8.33%) for ramps up to 30 feet long.

5. How long should a ramp be for a 2-foot rise?

Using a 1:12 slope:

$2 \times 12 = 24 \, \text{ft run}$

So, your ramp should be 24 ft long (plus small landings at both ends).

6. Do I need landings for long ramps?

Yes. Every 30 feet of horizontal run, you should include a level landing for resting and turning.

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