Calculate slope as a percentage grade, angle and ratio from rise and run.
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How do you calculate slope and grade from rise and run?
Grade = rise ÷ run × 100, angle = arctan(rise ÷ run), and slope length = √(rise² + run²). Use the same units for rise and run. For example, a rise of 1 over a run of 12 is an 8.33% grade, about 4.76°, or a 1:12 ratio — the common maximum for wheelchair ramps.
Understanding your result
Use the same units for rise and run. A 1:12 ratio (8.33%) is the common maximum for wheelchair ramps.
Formula and method
Grade = rise ÷ run × 100. Angle = arctan(rise ÷ run). Slope length = √(rise² + run²).
Worked example
A rise of 1 over a run of 12 is an 8.33% grade, about 4.76°, or a 1:12 ratio.
How to use this tool
- Enter the rise (vertical change).
- Enter the run (horizontal distance).
- Press Calculate.
About the Slope & Grade Calculator
The Slope & Grade Calculator turns a rise and run into a percentage grade, an angle in degrees and a ratio, plus the slope length.
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Frequently asked questions
What is a 1:12 slope?
It means 1 unit of rise for every 12 of run — an 8.33% grade, the usual accessibility limit for ramps.