Grade Formula:
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Percent grade is a measure of slope steepness expressed as a percentage. It represents the ratio of vertical rise to horizontal run multiplied by 100. This measurement is commonly used in road construction, civil engineering, and outdoor activities.
The calculator uses the grade formula:
Where:
Explanation: The formula calculates what percentage the vertical rise is of the horizontal run.
Details: Knowing the percent grade is essential for designing accessible pathways (ADA recommends ≤5% for wheelchair access), determining vehicle climbing ability, and assessing trail difficulty.
Tips: Enter both rise and run in the same units (feet in this calculator). Both values must be positive numbers. The run should be the horizontal distance, not the slope distance.
Q1: What's the difference between percent grade and degrees?
A: Percent grade is rise/run × 100, while degrees use arctangent of rise/run. 45° = 100% grade.
Q2: What is considered a steep grade?
A: For roads, ≥7% is considered steep. For hiking trails, ≥15% is steep. Wheelchair ramps should be ≤8.33%.
Q3: How do I measure rise and run in the field?
A: Use a level and measuring tape, or modern tools like laser distance measurers with inclinometers.
Q4: Can I use different units than feet?
A: Yes, as long as both rise and run use the same units, the percentage will be correct.
Q5: What does negative grade mean?
A: Negative grade indicates a downhill slope, though this calculator only handles positive values.