I went to Raster --> Analysis --> DEM (Terrain Models) to compute slope.

The slope ranges from 0-39.2311.

Now I'm unsure of the correct way to calculate slope between 5-10% in the raster calculator.


1 Answer 1


The definition is:

slope[percent] = tan(slope[degree])*100

but, Raster Calculator uses radians instead of degrees for trigonometric calculations. For this reason you have to use:

slope[percent] = tan((slope[degree]*3.141592653589793)/180)*100

Afterward, to select only slope percentages between 5-10% in the Raster Calculator, the expression it would be:

(("slope_percent@1" >= 5.) AND ("slope_percent@1" <= 10.))* "slope_percent@1"

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.