Slope calculator
Rise, run, length and grade
Enter any two values and the calculator works out the rest. Typing into a third field hands the oldest one back to the calculator.
Lengths can be in any unit, as long as all three use the same one.
Result
Your answer appears here as you type.
Slope calculator
Enter any two of rise, run, sloped length and angle to solve the rest. See the slope as degrees, percent grade, a 1:N ratio, a pitch and per mille.
Frequently asked questions
How is percent slope calculated?
Percent slope, also called grade, is the rise divided by the run, multiplied by 100. A path that climbs 5 m over 100 m of horizontal distance has a 5% slope, and a drain that falls 1 unit over a run of 50 has a 2% slope.
Percent is not the same as degrees: a 100% slope rises as far as it runs, which is 45°, not 90°. Enter any two of rise, run, length and angle above and the calculator shows the slope in degrees, percent, as a ratio and as a pitch.
How do you find the angle of a slope?
Divide the rise by the run and take the inverse tangent: angle = arctan(rise ÷ run). A slope that rises 1 m over a 4 m run is at arctan(1 ÷ 4), about 14°.
If you know the sloped length instead of the run, use the inverse sine: angle = arcsin(rise ÷ length). To measure the angle of a real slope, lay your phone on it and read the inclinometer.
Guides
About these measurements
Readings are estimates taken from rendered pixels and consumer device sensors. Do not rely on them for structural engineering, surveying, manufacturing inspection, navigation, or medical decisions. Check anything safety-critical with a calibrated instrument.
All processing happens in your browser. No image, camera frame or sensor reading is ever uploaded.
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