Slope Calculator
A slope is how steeply a surface climbs over a distance. Enter how far it rises and how far it runs, and this shows the same slope three ways.
- Free
- Works offline after your first visit
- Saves on this device
- No sign-up
- Updated
How it works
Divide the rise by the run to get the slope as a plain fraction. Multiply that by 100 to get a percent, the way road and roof grades are often written.
The angle is the arctangent of rise divided by run, in degrees. A 45 degree slope rises as far as it runs, so it is 100 percent.
Worked example
A rise of 18 in over a run of 10 ft is a slope of 15 percent, an angle of 8.5 degrees, or 6.7 of run for every one of rise.
Questions
What is a grade of 10 percent?
It means the surface rises 10 units for every 100 units it runs. Ten feet up over a hundred feet across is 10 percent.
Do I measure the run horizontally?
Yes. Run is the flat distance along the ground, not the length of the slope itself.
Can the slope be over 100 percent?
Yes. Steep ramps and some roofs go past it. A 100 percent slope is a 45 degree angle, and steeper slopes give bigger numbers.
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