Elevation Grade Calculator
Calculate slope as ratio, percentage, or angle for construction, hiking, surveying, and drainage projects
Slope Visualization
Calculation Results
Practical Applications of Elevation Grade
Construction & Engineering
Proper slope calculation ensures structural integrity in roads, ramps, and drainage systems. The ADA recommends a maximum 8.33% slope (1:12 ratio) for wheelchair ramps.
Hiking & Trail Planning
Evaluate trail difficulty before your hike. Grades over 20% are considered very steep and challenging for most hikers.
Landscaping & Drainage
Ensure proper water runoff with appropriate slopes. Patios and walkways typically require a minimum 2% slope for adequate drainage.
Roofing
Different roofing materials require specific minimum slopes. Asphalt shingles typically need at least a 4:12 pitch (18.4° angle).
Elevation Grade Formulas
Elevation grade (slope) is calculated using these fundamental formulas:
Basic Slope Calculation
Grade (Ratio) = Rise / Run
Grade (Percentage) = (Rise / Run) × 100%
Angle (Degrees) = arctan(Rise / Run)
Real-World Example
If a hill rises 25 meters over a horizontal distance of 100 meters:
- Ratio: 25:100 = 1:4
- Percentage: (25/100) × 100 = 25%
- Angle: arctan(25/100) ≈ 14°
How to Measure Slope in the Field
String Level Method
Stake one end of the slope, tie a string taught to the other end, use a level to ensure the string is horizontal, then measure the vertical distance from string to ground at the lower end.
Surveying Tools
Use a transit level, dumpy level, or laser level for professional accuracy. These tools provide precise elevation measurements over long distances.
Digital Tools
Modern smartphones with gyroscopic sensors or dedicated clinometer apps can measure slope angles directly when placed on the incline surface.
Common Slope Examples
| Slope Description | Ratio | Percentage | Angle | Typical Use |
|---|---|---|---|---|
| ADA Ramp Maximum | 1:12 | 8.33% | 4.76° | Wheelchair accessibility |
| Gentle Hill | 1:10 | 10% | 5.71° | Easy walking |
| Moderate Slope | 1:5 | 20% | 11.31° | Moderate hiking |
| Steep Hill | 1:3 | 33.33% | 18.43° | Challenging terrain |
| Baldwin Street (Steepest) | 1:2.86 | 35% | 19.29° | World’s steepest residential street |
| Extreme Slope | 1:2 | 50% | 26.57° | Very difficult climbing |
Frequently Asked Questions
Elevation grade (or slope) is the steepness or degree of inclination of a surface. It describes how much vertical change occurs over a specific horizontal distance.
Slope percentage represents the vertical rise per 100 units of horizontal distance. Angle is the actual incline measured in degrees. A 100% grade equals a 45° angle, not 90° as sometimes mistakenly assumed.
Baldwin Street in Dunedin, New Zealand holds the Guinness World Record with a maximum grade of 35% (approximately 19° angle). This means for every 2.86 meters horizontally, the road rises 1 meter vertically.
Most building codes recommend a maximum driveway slope of 15-20%. Slopes steeper than 20% can be challenging for vehicles, especially in icy conditions.
Yes! A 100% grade means the rise equals the run (45° angle). As slopes approach vertical (90°), the percentage approaches infinity. A 45° angle is 100%, while a 63.4° angle is 200% grade.