1. What Is Percent Grade Slope?

Percent grade slope represents the steepness of a slope expressed as a percentage. It indicates how much a surface rises vertically for every 100 units of horizontal distance.

2. How Does The Calculator Work?

The calculator uses the percent grade formula:

Where:

• \( Rise \) — Vertical height difference (feet)
• \( Run \) — Horizontal distance (feet)
• \( 100 \) — Conversion factor to percentage

Explanation: The formula calculates the ratio of vertical rise to horizontal run, then multiplies by 100 to express as a percentage.

3. Importance Of Slope Calculation

Details: Percent grade calculations are essential in civil engineering, road construction, landscaping, wheelchair ramp design, and determining vehicle climbing capabilities.

4. Using The Calculator

Tips: Enter rise and run values in feet. Both values must be positive numbers. The result shows the slope percentage.

5. Frequently Asked Questions (FAQ)

Q1: What is considered a steep slope?
A: Generally, slopes above 15% are considered steep, while slopes above 25% are very steep and may require special engineering considerations.

Q2: How does percent grade relate to degrees?
A: Percent grade = tan(angle) × 100. For example, a 45° angle equals 100% grade.

Q3: What is the maximum grade for roads?
A: Most highways have maximum grades of 6-8%, while mountain roads may reach 12-15%. Steeper grades require special design considerations.

Q4: How is slope measured in the field?
A: Using inclinometers, laser levels, or smartphone apps that measure tilt angles, then converting to percent grade.

Q5: Why use percentage instead of ratio?
A: Percentage is more intuitive for most people and directly shows how many units of rise per 100 units of run.