Climbing Classes and Ratings: YDS Yosemite Decimal System 1-4

YDS Yosemite Decimal System -climbing-grades-and-ratings

The YDS Yosemite Decimal System rates mountain activities (hiking and rock climbing) as class 1 to 5, in increasing order of difficulty. Class 5 (technical climbing generally requiring rope & gear) has the most extensive array of subdivisions. There is an unofficial Class 6 which generally means “utterly unclimbable free solo, requires aid &/or ladders”.

But before we get into the actual classes, lets talk about personal assessment of route difficulty, vs. your ability… that’s supposed to be the point of ratings, anyways: to allow you to choose routes and expeditions that your present skills are adequately prepared for, and to plan for appropriate protection, gear, training and risk assessments. That said:

Assessing Risk & Difficulty of a Climb

Most importantly, the established or guidebook “rating” (generally YDS Yosemite Decimal System or some variant) of any given climb in the wild should be seen as a *starting* point, not as a definitive. There are many modifiers which can make any given route substantially easier, or in most cases, much harder.

Your initial assessment of any given route will take into account the following:

  • the steepness of the slope
  • the type of substrate
    • rock, snow, ice, mixed
  • the stability of the substrate
    • rock solid vs. unstable (and everything in between)
    • granite vs. sandstone vs. blue ice vs. slush vs. scree
    • *see: all holds have a timer on them
  • the pattern of the holds / the actual route
  • the exposure
    • if you fall, how badly might you be hurt?
    • exposure measured by two factors:
      • height of fall prior to stoppage
        • stoppage = object that breaks the fall: plateau, tree, rock, etc.
      • landing – what you will hit on impact
        • examples: sharp rocks, treetops, grass, deep snow, deep water, etc.

You attempt to do a lot of this in advance, by studying topos and reading the ubiquitous trip reports which populate AllTrails, Reddit, and others (which are of highly variable depth, quality, accuracy and humor). And reading the YDS Yosemite Decimal System grade — which, notably, refers only to the “crux,” that is, the most difficult portion of the path. That’s the starting point. The pre-trip planning.

But what really matters is your assessment of the route on site. Standing right in front of it. In parallel, you need to perform an accurate-as-possible self-assessment: How are you feeling? Are you injured? Well-nourished? Well-rested? Tired? Confident?

And, of course, there is the Mood of the Mountain, aka:

YDS Yosemite Decimal System MODIFIER: Weather

Weather Matters!

After all that, take into account the weather: both as it is at present, and as it will be once you are halfway up the slope.

The same terrain visited twice can be almost unrecognizable in adverse weather conditions. A route that is trivial in late summer / early fall can be treacherous and/or utterly impassible in winter (a few mountaineering routes, which require snow / ice bridges, are the reverse: doable in winter, impassible in summer).

Weather elements to consider include:

  • temperature
    • climbing a 5.9 is VERY different in these two scenarios:
    • bare handed with climbing shoes
    • wearing liners, gloves, heavy boots and spikes
  • wind
    • again, hugging the rock with toes on a ridge in calm air is one thing
    • now try that same trick being hit with 50mph gusts
  • base
    • is your route / portions of route covered in snow and/or ice?
    • how deep is the snow?
    • what is its ability to hold an anchor / axe?
    • is there an avalanche hazard / risk?
  • precipitation
    • climbing a wall in the rain,
    • add + three decimals on the YDS
    • precipitation (rain / snow) also adversely effects both:
      • visibility / ability to sight next waypoint / trail
      • ability to communicate with team at distance

In summary, a 5.3 route in the summer could be a 5.9 route in a snowstorm in deep winter. Welcome to the unpredictability of mountaineering.

This goes equally for “trails” as well as “climbs”… under heavy snow, a trail can become effectively non-existent, when all visible markers are buried under 1-3 feet of snow. This is typically resolved in the Rockies with *very large* — as in, 8 foot tall — rock cairns which hikers regularly add to during passage. But the biggest cairns I’ve found in the Sierras so far are between 6-12 inches high, a few rocks at best. And many of those, from my observation, haven’t even been “on trail.” They simply marked the way that a certain individual chose to move & mark that day.

So that’s your personal assessment. Know your abilities. Check the weather. Proceed with caution.

Now, onto the “formal” ratings:

YDS Yosemite Decimal System 1-4

…expanded with Sierra Club Mountain Scrambling subGrades

The simple class definitions 1-4 of the YDS Yosemite Decimal System are as follows. The sub-grades, indicated by the “S-” prefix, are created by the Sierra Club to add useful risk assessment / planning information to each grade:


Hiking on trails
and easy cross-country travel with little risk.

S-1.0 Hands-in-pockets walking on well-maintained trails.

S-1.1 Hikes predominately on a mix of maintained and/or use trails.

S-1.2 Intermediate to long distances of cross-country travel over stable terrain of low to moderate grade.


Simple scrambling and rough cross-country travel on scree, talus and boulders,
with minimal exposure and low to moderate risk.

S-2.0 Modest distances of rough cross-country travel on low angle scree and talus, with only short segments of easy scrambling on moderate angle, stable terrain.

S-2.1 Short to intermediate distances of rough cross-country travel on low angle scree, talus and boulders, with extensive, easy scrambling on moderate angle terrain that is predominately stable.

S-2.2 Intermediate to longer distances of rough cross-country travel with lengthy stretches of easy to medium difficulty scrambling on moderate to fairly steep angle scree, talus and boulders that are sometimes unstable.


Moderate scrambling on steep, rocky terrain
that requires handholds for upward movement and safety.
Beginners may want a belay due to increased exposure and risk of serious injury.

S-3.0 Brief, medium difficulty to hard scrambling on fairly steep to steep angle, stable rock with medium to high exposure.

S-3.1 Short to intermediate length, hard scrambling on fairly steep to steep angle and predominately stable rock with high exposure.

S-3.2 Extensive, hard scrambling on fairly steep to steep angle and sometimes unstable rock with high to severe exposure.


Difficult and exposed scrambling on very steep terrain
where a rope is often advisable for safety,
given the substantial risk of serious injury or death in the event of a fall.

S-4.0 Brief, very hard scrambling on extremely steep, stable rock with high to severe exposure.

S-4.1 Short to intermediate length, very hard scrambling on extremely steep and predominately stable rock with severe exposure.

S-4.2 Extensive, very hard scrambling on extremely steep and sometimes unstable rock with severe exposure.

These definitions are courtesy of the Sierra Club (*which now calls class 1-4 “Mountain Scrambler Ratings“, to formally separate them from the highly technical YDS Yosemite Decimal System Class 5 grades). The Sierra Club originally standardized the system in the 1950s (it has been continually modified and tweaked ever since. Globally, there are at least 6 competing ratings systems)


# # #

G R E G O R Y ‘ S . M O U N T A I N S