Ski Slope Ratings Explained

Ever wondered what the difference between a Green and a Blue is? A Black Diamond and a Double-Black? Ski expert Aaron Bandler explains.

Photo by Daniel Frank
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Almost ubiquitously, ski resorts in North America rate their terrain according to its difficulty with a simple rating system of color-coordinated symbols.

Four grey squares each depicting a ski slope rating: a green circle labeled "easiest," a blue square labelled "more difficult," a black diamond labelled "most difficult," and two black diamonds labelled "experts only."
Graphic by Aaron Bandler
  • Green Circle: Easiest
  • Blue Square: More Difficult
  • Black Diamond: Most Difficult
  • Double Black Diamond: Experts Only

These are the main ratings you will see at pretty much every ski area in the United States and Canada.

So what do they mean?

Green Circle

Casually referred to as “green runs” or just “greens” (but never “circles”), these are beginner runs that are great for those just getting the feel for being on snow. Sometimes you’ll hear people refer to the “Bunny Hill” or “Bunny Slope,” which usually means a specific area of the mountain (usually near the lodge or base area) that has the easiest runs and is specifically for beginners. But there are also green runs all over the mountain. Beginner skiers who have “graduated” from the bunny hill can venture to other areas of the mountain and find accessible runs that are usually wide, have a low slope angle (i.e. not steep), and are usually groomed (when a snow cat flattens the snow surface).

A snowboarder makes their way down a groomed run
A good example of a Green Circle. This run is groomed, not very steep, and wide open. Photo by Photomix Company

Blue Square

Blue Squares aka Blue Runs aka Blues (but never just “squares”) are intended to be intermediate runs. The “Blue Square” rating casts a wide net across a lot of different types of terrain. This could mean a wide open groomed run (aka “groomer”) similar to a green but steeper. It could also mean an ungroomed, lower-angle run that will develop moguls. Regardless, blue runs are accessible to skiers with the confidence to control their speed, but who are still developing the technique to handle steeper or otherwise rougher terrain.

Many skiers and snowboarders make their way down a tree-lined run
This run is a pretty typical-looking Blue Square. The run is steep enough that you could pick up a lot of speed if you went straight down it, but it’s wide enough and flattens at the bottom so you could stop yourself with room for error. Photo by Jure Širić

Black Diamond

Black Diamond aka Blacks (but never “diamonds”) are challenging runs for more advanced skiers who are more confident in their own skill level. These may be steep slopes that are groomed or ungroomed, and have obstacles such as rocks and trees. Confidently navigating a black requires skill and experience, but many blacks are still accessible to intermediate skiers who are up for a challenge and willing to take it slow. Certain ski areas that have high alpine bowls - terrain that is above treeline, wide open at the top and narrowing downwards - will rate the more mellow slopes of the bowl as black diamond, and reserve the more aggressive slopes in the same bowl for double black diamond status. That’s right - two different descents on the same slope can have two different ratings!

A black and white photo of a ski hill with steep runs in the foreground and a chair lift
Some beautiful Black Diamond terrain. The terrain is not scary-steep, but it’s varied (some steep sections, some more mellow), ungroomed, and there are definitely obstacles in the form of trees and rocks. Photo by Mali Maeder

Double-Black Diamond

“Double-Blacks” are for expert skiers. These are often on the steepest, most challenging terrain in a ski area. In some cases, the majority of the run itself may not be any more challenging than a regular black, but it may have a short section that requires expert technique, such as a vertical drop or cornice to get onto the main slope, or a narrow “chute” between rocks or trees. Skiers who think they are ready for the challenge of a double-black should consider not just how the run looks as a whole, but how the most difficult section of the run looks. So maybe you can ski the main slope, but if you have to drop a cornice to get onto it and you don’t make the landing, are you going to go tumbling down the mountain? Double-blacks can be unpredictable, and what may look accessible from the chairlift almost always looks different when you’re standing on top looking down.

A skier turns on a steep run overlooking mountains
A gorgeous Double-Black Diamond. This run is long and steep and has untamed features like this lip of windblown snow. Photo by Fede Roveda

Exceptions and Variations

The four ratings described above probably account for 90%+ of ski runs in North America, but there are some variations though that you may encounter.

Double-Green Circle

Sometimes, ski areas will select the easiest, most forgiving terrain on the mountain and give it a double-green circle. Just like a double black is extra challenging, a double-green is extra easy. If your ski area has any runs with this rating, these areas are typically where you will start if you are taking a first-time lesson. They may not even be accessed by a traditional chairlift, but rather a rope-tow or “magic carpet” (conveyer belt).

Combined Ratings

Some ski areas have runs that have a combined rating of green/blue or blue/black. These can be confusing. Essentially, the ski area is trying to let skiers and snowboarders know that the run is in between two different ratings.

Two grey squares framing graphics depicting combined ratings: a blue square with a green circle in the center and a blue square with a black diamond in the center
Graphic by Aaron Bandler

Green/Blue Some days, a run might ski like a green, but other days, it may be more difficult if, for example, the snow conditions are more icy or more choppy. Or perhaps, an easy run is slightly narrower than might be expected, and if it is a busy day on the slopes, the extra people create more of a challenge that makes it ski more like a blue trail.

Blue/Black A Blue/Black run could be a slope that skis differently depending on the snow conditions, or one that has varied terrain for skiers of differing skill levels. For example, a run that has steep sections may still fall into blue territory when it is groomed, but if it becomes icy, it will require more skill and therefore will feel more like a black. On the other hand, a run that has variable steepness and amount of obstacles might be a Blue/Black as well. For the skier who wants the Black Diamond experience, they could choose the more challenging descent that brings them through a mogul field and a patch of trees, while the more intermediate skier can take an easier descent that avoids these features. There are no set guidelines for combined runs and resorts will set these ratings at their own discretion. It can be a bit confusing to the unfamiliar, which is why these tend to be more rare ratings.

Double-Black Extreme Terrain

A grey square with two black diamonds, one each with an E and an X at the center. Words at the bottom read "extreme terrain"
Graphic by Aaron Bandler

This is the real-deal don’t-say-we-didn’t-warn-you/skull-and-crossbones terrain. These are typically designated by a double-black diamond icon with the letters “E” and “X” in the diamonds. If double-blacks are for experts only, Extreme Terrain is REALLY for experts only. Seriously.

Sometimes visitors to ski resorts can be tempted by the feeling that a ski area is similar to Disneyland, and that everything is safe and nothing can really hurt you even though it may look scary. Every season, ski patrol performs rescue after rescue of injured skiers and snowboarders who want the bragging rights of having skied Extreme Terrain.

Just because you can get there by riding a lift does not mean it’s safe. These runs often feature very steep slope gradients, narrow couloirs (a narrow chute usually between two rocks), cliffs, unmarked rocks and trees, and no-fall-zones (areas where a fall could mean a tumble over a cliff), not to mention other hazards such as avalanches. While ski areas do take steps to mitigate avalanche risk and only open avalanche-prone slopes when they deem appropriate, snowpack can be unpredictable and avalanches do happen, and do cause fatalities at ski areas. Don’t take the risks of skiing Extreme Terrain lightly.

Three skiers make their way along a snowy and windy ridge
In a lot of cases, Extreme Terrain is only accessible by hiking beyond the chairlift. The hike may be as dangerous as the descent, as you battle wind, exposure, and altitude. Photo by Guillaume Groult

Orange Oval

A grey square with an orange oval at the center and the words "terrain park" at the bottom
Graphic by Aaron Bandler

The orange oval icon designates freestyle terrain, and is typically reserved for terrain parks and halfpipes. These are the man-made features where skiers and snowboarders can test their skills on engineered jumps, rails, boxes, and pipes.

A skier in an orange jacket crosses their skis behind them as they execute a jump
The “Orange Oval” runs are probably where most injuries occur at any given ski area! Photo by Felipe Giacomett

In conclusion, there is a standardized system for rating ski slopes, but there is no standardization in deciding which rating to apply to any given slope. Each resort rates its own terrain, and one area’s blues may feel more like a different area’s blacks and vice versa. Some regions of the continent are just steeper in general than others, so you may experience some geographical differences as well.

When talking with your ski or snowboard expert, let them know which types of runs you generally prefer to spend most your day on. If you’re a confident Blue-skier and have tried a Double-Black once and made it out alive, let us know! We want to help you get on the gear that will fit your current experience level, but if you are looking for equipment to grow into as you progress to more and more terrain, we can help you with that as well!

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Written By
By day, I am a hydrogeologist in the Denver area, but my passion for skiing goes much deeper than my current career. I started skiing at age 4, and I haven't missed a season. I've been skiing longer than I've been doing just about anything else, and have filled my winters with racing, ski-bumming, a...

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