Difficulty rating

Hiking and Climbing
Routes on 14ers.com have been assigned a difficulty rating using the Yosemite Decimal System (YDS), which has been in use in the United States for over 75 years.
 
The system uses "classes" ranging from 1 (easiest) to 5 (most difficult).
In some cases, routes are described a as "Difficult Class 2", or "Easy Class 3" to provide more detail:
 
Class 1
Easy hiking - usually on a good trail.
 
Class 2
More difficult hiking that may be off-trail.
You may also have to put your hands down occasionally to keep your balance. May include easy snow climbs or hiking on talus/scree. Class 2 includes a wide range of hiking and a route may have exposure, loose rock, steep scree, etc.
 
Class 3
Scrambling or un-roped climbing.
You must use your hands most of the time to hold the terrain or find your route. This may be caused by a combination of steepness and extreme terrain (large rocks or steep snow).
 
Class 4
Climbing. Handholds and footholds are required for upward or downward progress. Rope is sometimes used on Class 4 routes because falls can be fatal. The terrain is often steep and dangerous.
 
Class 5
Technical climbing.
The climbing involves the use of rope and belaying. Rock climbing is Class 5. Note: In the 1950s, the Class 5 portion of this ranking system was expanded to include a decimal at the end of the ranking to further define the difficulties of rock climbing.
 
This is called the Yosemite Decimal System (YDS). The decimal notations range from 5.1 (easiest) to 5.14 (most difficult). Recently, the rankings of 5.10 through 5.14 were expanded to include an "a", "b", "c" or "d" after the decimal (Example: 5.12a) to provide further details of the ranking. None of the routes described on 14ers.com are Class 5, so I will not go into detail of the expanded decimal system.
 
Snow Steepness
 
Easy 0-30 Degrees
Moderate 30-45 Degrees
Steep 45-60 Degrees
Very Steep 60-80 Degrees
Vertical 80-90 Degrees
 
Backcountry Skiing
For ski routes, the simple Novice/Intermediate/Advanced/Extreme scale is used. A novice-rated 14er ski route does not mean it's as easy as a green trail at the ski area - it means the route is recommended for novice backcountry skiers who have at least some mountaineering experience and solid skiing skills.
 
On the other end of the scale, extreme routes have a slope angle greater than 45° and likely include terrain features which may complicate your descent. Skiing a 14er is much different than visiting the ski area and the route difficulties should not be compared directly to ski area standards.
 
 
For many ski routes, we have also included the "D System" by Lou Dawson. A specific set of skills is required to ski in the backcountry and ski routes can be steep, dangerous, and difficult. On many routes, a fall could be fatal.

THE STEEPS: 
Slope angle plays a large part in the difficulty of a ski route. An advanced slope will often exceed 40 degrees. If a slope is over 45 degrees, it is usually difficult to stop a fall.
 
A fall on a slope over 50 degrees could result in your demise.
 
The first time I looked down a long 55 degree slope, my brain had trouble forcing my skis over the edge.
 
Few ski areas in North America have any runs that exceed 55 degrees.
 
Silverton Mountain ski area, in Colorado, has some of North America's steepest ski area terrain - with maximum angles of 55 degrees.
 
Learn to ski steep runs at the ski area before heading to a steep backcountry route. It's vital to master the "jump-turn" technique.
 
The jump-turn is useful on steep, narrow routes where carving is difficult. Expect to see ski tracks on terrain that you consider unsuitable for anyone with a brain. Another person's idea of advanced or extreme may differ from your own.

TERRAIN + CONDITIONS = LEVEL OF DIFFICULTY: 
Steepness is not the only factor when determining the difficulty of a backcountry ski route.
 
At a minimum, consider the following factors when planning a descent: Slope angle, snow condition, avalanche danger, sun hit, cliffs, rocks, ICE or hard snow, route exits, run-out, wind, and visibility. It's a great idea to climb what you are going to ski.
 
If you feel it's too steep to climb, then it's probably too steep for you to ski. During a climb, you will be able to identify the desired path of your descent.
 
You may also spot that drop-off that you can't see from the top. It's critical to know when something is beyond your ability before you are in a tough situation.  If you are an expert ski mountaineer, you will eventually peer down your first "no-fall" route. This is usually a good time to consider your future in the backcountry. Don't fall.