# Black diamond

### From Fiswiki

** Black diamond**,

**Difficult**Amongst the most difficult at a given mountain.

**Black Diamond**trails tend to be steep (typically 40% and up) and may or may not be groomed, though the introduction of

**winch-cats**has made the grooming of steep slopes both possible and more frequent.

## [edit] **Slope Steepness**

There are two ways of measuring slope steepness. The first is a measurement using **degrees**, which measures the angle of the slope in degrees from the horizontal. The second is a percentage.

This is calculated using the formula 100*rise/run. Rise is the vertical change and run is the horizontal distance. A 100% slope is angled at 45 degrees.

- 10% is equivalent to 5.71º
- 20% is equivalent to 11.31º
- 30% is equivalent to 16.7º
- 40% is equivalent to 21.8º
- 50% is equivalent to 25.67º
- 75% is equivalent to 36.8º
- 100% is equivalent to 45º

A beginner slope is typically between 6% and 25%. Intermediate hills range from 25% to 40%, and expert is 40% plus.

## [edit] **Also see**

**Green circle****Blue Square****Black diamond****Double black diamond****Skier Rider Ability Level****Slope****Grade****Inclinometer****Mountain****Degree****Average Grade****Trail System****Average Grade****Average Width****Mountain master planning process****Maximum Grade****Ski resort**

## [edit] **Reference**

- Wikipedia
*Ski trail ratings*[1]

Return to **Trail designation system**, **Ski lift**, **Ski Related Definitions**, **Freestyle Equipment Rules**, **General Definitions** or **Freestyle Skiing**