What's the Difference Between Percent Grades and Degrees?
When it comes to measuring the steepness of a hill or slope, you might come across two different units of measurement: percent grade and degrees. To the untrained eye, these two units might seem interchangeable—but they're actually quite different. In this blog post, we'll explain the difference between percent grade and degrees to help with understanding the local requirements for maximum grade when it comes to driveway construction.
How Percent Grade is Calculated
Percent grade is calculated by determining the amount of rise over the amount of run (the horizontal distance) and then converting that figure to a percentage. For example, if a slope has a rise of 6 feet and a run of 100 feet, the percent grade would be 6%. You can also calculate percent grade using this formula: Percentage = (Rise/Run) x 100.
How Degrees are Calculated
Degrees, on the other hand, are calculated by finding the angle formed by the line of slope and the horizontal line. To do this, you'll need a scientific or graphing calculator with trigonometric functions. Once you have your calculator, use these steps to find the angle in degrees:
1. Enter the value of the rise (the vertical distance).
2. Press the INV button.
3. Enter the value of the run (the horizontal distance).
4- Press the TAN button. The answer will be displayed in degrees!
5. Use this formula to convert degrees to percent grade: %grade = Tangent(angle)*100
For Example, 45° is 100% grade because the rise is equal to the run.
Your vehicle may have an inclinometer tool built-in, but it usually reads in degrees, which can be misleading. The degrees will always be lower than percent grade. Using the inclinometer on your vehicle will not convey an actual reading of how steep your driveway is relative to the max percent grade requirements, 17% (9.65°) in Teller County, and 12% (6.84°) in Park County, for driveways over 150ft long.
As a professional Full Excavation Contractor, Peak DirtWorks specializes in ensuring your driveway layout works with the slope of your property to meet the County code requirements by using our advanced laser technology and equipment, specifically the Spectra Precision GL622N Dual Grade Laser w/ RC602N remote Control w/ the Spectra Precision HL760 receiver.