Grade Percent Calculator
Convert a slope grade in percent to its angle in degrees, as used for roads, ramps, and treadmills.
- Rise per 100 units of run
- 10
Formula: angle = arctan(grade / 100)
About Grade Percent Calculator
Grade Percent Calculator is a free online calculator that gives you an instant, accurate result as you type. Convert a slope grade in percent to its angle in degrees, as used for roads, ramps, and treadmills.
The calculation uses the standard formula angle = arctan(grade / 100) and updates live with every change to the inputs. Everything runs client-side in your browser — fast, private, and free to use as often as you like.
A 100% grade is a 45-degree slope, not vertical — grade is rise divided by horizontal run, times 100.
Frequently Asked Questions
Is Grade Percent Calculator free to use?
Yes. Grade Percent Calculator is completely free, with no sign-up, no downloads, and no usage limits. You can use it as many times as you like on any device with a web browser.
How accurate is this calculator?
The calculator applies the standard formula (angle = arctan(grade / 100)) with full floating-point precision and rounds only the displayed result. For most practical purposes the results are exact.
What is a typical maximum road grade?
Most highways are kept under 6-7% grade; wheelchair ramps are usually limited to about 8.33% (a 1:12 slope, roughly 4.76 degrees).
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