Measuring Slopes of Accessible Routes for ADA Compliance with Just Your Cell Phone

Written By PI

Keeping your parking lot accessible is not just about painting blue stripes. One of the most common ADA issues is slope, especially in accessible parking stalls, aisles, and the routes leading to your building.

The good news is that you do not need an expensive survey tool to do a quick check. With a free app called Bubble Level, available in the Apple App Store and Google Play Store, you can measure slopes in decimal degrees right from your smartphone.

ADA Slope Requirements (Simple Version)

  • Accessible parking stalls and access aisles: Must be almost flat, no more than 2% slope (1:48) in any direction.

  • Cross slope of walkways: Maximum 2% side-to-side.

  • Accessible routes (sidewalks/walkways): Up to 5% running slope without being considered a ramp.

  • Ramps: Maximum slope of 8.33% (1:12) if you provide handrails and landings.

How to Use the Bubble Level App

  1. Download Bubble Level (free) from the App Store (iPhone) or Google Play (Android).

  2. Open the app, which will display slope in decimal degrees (for example, 1.4°, 2.7°).

  3. Place the flattest edge of your phone on the walking surface (probably the top if it doesn’t have buttons)

  4. Read the angle shown and compare it to the chart below.

Tip: For better accuracy, set your phone on a small straightedge or carpenter’s level instead of directly on rough pavement.

Converting Decimal Degrees to Percent Slope

Since ADA rules use percent slope, here are the conversions you actually need:

Quick Reality Check

  • If Bubble Level shows 1.0°, you are roughly at 1.7% slope, which is safe for parking stalls.

  • If it shows 2.0°, you are at 3.5% slope, which is fine for a walkway but too steep for a stall.

  • If it shows 5.0°, that is 8.7% slope, right at the edge of ramp compliance.

Key Takeaways

  • 1° ≈ 1.7% slope, almost flat.

  • 2° ≈ 3.5% slope, too steep for stalls, acceptable for short routes.

  • 3° ≈ 5.2% slope, considered a ramp.

  • 5° ≈ 8.7% slope, maximum ramp slope allowed.

The Bubble Level app is not a substitute for a professional ADA survey, but it is a quick and free way to flag areas that may need attention.

PI