Grade/Slope Calculator
Calculates slope percentage, grade ratio, and elevation change between two points
Vertical change in inches
Horizontal change in inches
Grade expressed as a percentage
Slope angle in degrees
Slope expressed as a ratio of 1:X
Frequently Asked Questions
What is grade or slope?
Grade or slope describes how steep a surface is. It is the ratio of vertical rise to horizontal run. A 5% grade means the surface rises 5 feet for every 100 feet of horizontal distance. It is used in construction, road design, and drainage planning.
How do I convert slope percentage to degrees?
Use the arctangent function: angle = arctan(slope / 100). A 100% slope equals 45 degrees. A 10% slope is about 5.7 degrees. Slope percentage and degrees are not linearly related, so you cannot simply divide by a fixed number.
What is a 1:12 slope ratio?
A 1:12 ratio means 1 unit of rise for every 12 units of run. This equals an 8.33% grade or about 4.76 degrees. The ADA requires ramps to have a maximum slope of 1:12 for wheelchair accessibility.
What slope is needed for proper drainage?
A minimum of 1-2% slope (1/8 to 1/4 inch per foot) is needed for surface drainage away from buildings. Gutters and downspout extensions should maintain at least 1% slope. Steeper slopes drain faster but may cause erosion.
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