Slope Stability / Safe Gradient Checker
Convert slopes between percent, degrees, and rise:run ratio, then compare against rule-of-thumb guideline ranges for different use cases like driveways, paths, ramps, and yards.
Slope Input
Slope as a percentage (rise/run x 100). E.g., 10% = 10 ft rise per 100 ft run.
Use Case Context
Different use cases have different acceptable slope ranges. Select the context that best matches your application.
Vehicle Driveway Guidelines
For vehicle driveways: Recommended max 10%, typical max 15%. Steeper driveways can be difficult in icy conditions.
Custom Maximum (Optional)
Optional: Enter your own maximum slope percentage to compare against.
Check Your Slope Gradient
Enter a slope as percent, angle, or rise:run ratio to see how it compares against rule-of-thumb guidelines for different use cases.
Input Options
%, Degrees, Ratio
Contexts
5 Use Cases
Fill in the form and click "Check Gradient" to see results
Understanding Slope Gradients
What Is Slope?
Slope describes how steep a surface is relative to horizontal. It can be expressed in several ways:
- Percent Grade (%): The rise divided by run, multiplied by 100. A 10% slope means 10 feet of vertical rise for every 100 feet of horizontal distance.
- Angle (Degrees): The angle from horizontal, measured in degrees. A 45° slope is very steep (100% grade).
- Rise:Run Ratio: Expressed as "1:X" where X is the horizontal distance for 1 unit of vertical rise. A 1:12 slope means 1 foot rise for every 12 feet of run.
Common Slope Conversions
| Percent | Degrees | Ratio (1:X) | Description |
|---|---|---|---|
| 2% | 1.1° | 1:50 | Nearly flat |
| 5% | 2.9° | 1:20 | Gentle (accessible ramp target) |
| 8.3% | 4.8° | 1:12 | ADA maximum ramp slope |
| 10% | 5.7° | 1:10 | Moderate (comfortable driveway) |
| 15% | 8.5° | 1:6.7 | Steep driveway |
| 25% | 14° | 1:4 | Very steep for walking |
| 33% | 18° | 1:3 | 3:1 slope (landscape max) |
| 50% | 27° | 1:2 | 2:1 slope (engineering cutoff) |
| 100% | 45° | 1:1 | 1:1 slope (very steep) |
Context-Specific Guidelines
Different applications have different acceptable slope ranges. These are general rule-of-thumb guidelines, not building codes:
Accessible Ramps
- Recommended: 5% (1:20)
- Typical max: 8.3% (1:12)
- ADA codes have additional requirements beyond slope
Pedestrian Paths
- Recommended: 5% or less
- Typical max: 10%
- Steeper paths can be slippery when wet
Vehicle Driveways
- Recommended: 10% or less
- Typical max: 15%
- Steeper driveways problematic in icy conditions
Yard / Lawn Areas
- Recommended: 15% or less
- Typical max: 33% (3:1)
- Steeper slopes hard to mow and maintain
What This Tool Does and Doesn't Do
This Tool DOES:
- Convert slopes between percent, degrees, and ratios
- Compare your slope against rule-of-thumb guidelines
- Classify slopes as gentle, moderate, steep, or very steep
- Help you understand relative steepness for different uses
This Tool Does NOT:
- Perform geotechnical slope stability analysis
- Determine if a slope is "safe" or "stable"
- Confirm ADA or building code compliance
- Account for soil type, drainage, or vegetation
- Replace professional engineering review
When to Consult a Professional
Seek Professional Help For:
- Any slope that will support structures or vehicles
- Accessibility ramp design (ADA compliance)
- Slopes above 50% (2:1) that need to remain stable
- Sites with poor soil conditions or high water tables
- Retaining walls or slope stabilization projects
- Commercial or public projects with code requirements
- Any situation where slope failure could cause injury or property damage
Frequently Asked Questions
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