% grade converted to degrees????

[NHski]

anybody know how to do this?

[elwood]

Not quite what you are looking for, but close. Good info/ here anyway... http://www.keigansystems.com/Support/HowDoI/GRD/Gradient.pdf

[TheOctopus]

Here's the math:

% slope = 100 times the tangent of the slope angle

To go the other way and convert slope angle to percent grade, take the arctangent ("arctan" or "tan-1" on your scientific calculator) of the percent grade (expressed as a decimal, not a percentage).

A few examples. 45 degrees is 100%. As you approach vertical -- 90 degrees, a.k.a. a cliff -- the percent grade approaches infinity. As you approach a flat piece of ground (a.k.a. Ohio, where I just moved), percent grade approaches zero. A 25 degree slope (a black diamond at most places) is a 47% grade. A 40 degree slope (certainly a double-black diamond anywhere, and a rare find in-bounds in the East) is an 84% grade.

Don't be fooled by your friends' talk of that "schweet 70 degree coolie" they just bagged. They're confusing slope angle and percent grade, a common mistake. Even Las Lenas (the ski area, not our amigo) is guilty of this. They list their on-piste terrain as between "12% and 53%" which would give them a maximum in-bounds slope of less than 30 degrees. Oops. Usually ski areas make the "mistake" the other way around to make their place sound gnarly steep.

[Mumster]

NHski:
If you want to estimate, for the most part the grade of a ski slope is about twice its inclination. So a 45 degree slope is around a 90% grade; a 30 degree slope is around a 60% grade, etc. The rule doesn't work at the extremes, but it is a reasonable ballpark estimate for most slopes.

[NHski]

I have actually created an excel spreadsheet that can convert the two now. Boy, I have way too much free time at work!