A skier takes measured turns down a steep, bumpy run at Beaver Creek Resort. You can see more ski runs on an adjacent slope and rugged mountains in the background

Ski Slope Ratings Explained

So, you want to get into skiing but have some questions about slope ratings and trail difficulty. Well, you’re in the right place! Ski slope ratings are important because good trail selection can help prevent accidents and falls.

The North Americas ski rating system helps decrease your risk of stumbling down a scary run. As long as you understand the color-coordinated symbols and trail signs, on-mountain navigation becomes a lot more enjoyable.

In this guide, I’ll break down the different slope ratings in North America and how they’re calculated. I’ll also go over rating systems in other parts of the world and what to do if you end up on a slope that’s too difficult to ski. With this information, you’ll be able to pick and choose the best terrain for you.

What Are Ski Slope Ratings?

Ski ratings are applied to all ski slopes. By categorizing slopes, ski resorts make it obvious which runs are meant for which level of skier. 

Slopes with a green circle next to the name are for beginners. Slopes with a blue square are intermediate, and black diamonds symbolize the hardest runs on the mountain. If you're a first-time skier, you do not want to end up on expert trails.

The slope rating is typically right next to the name of the ski run and posted on all large ski slope signs. 

How Are Ski Slope Ratings Calculated?

Ski slope ratings are calculated in a few ways. One of the most important elements is how steep the slope is. Steepness is measured in percentages and degrees. Ski resorts tend to use percentages (slope gradient), while backcountry terrain is best evaluated in degrees.

Steepness isn’t the only factor in ski ratings, however. Some ski runs have hazards and obstacles like trees, bumps, and rollers (abrupt changes in pitch), which also affect the difficulty. If a ski run has a lower average gradient range but is rated difficult, it means there are likely hazards.

While most North American ski resorts use the same color system, the difficulty varies between resorts because each one is responsible for labeling its own terrain. Resort A may label something an expert run, while a similar slope gradient at resort B would be labeled intermediate. 

Generally, despite non-standardized rating criteria, every resort wants a mix of all three ratings to appeal to the widest variety of skiers. That means that even at a resort known for challenging terrain, you’ll be able to find ski runs that match your ability level.

Green Ski Slopes

  • Ability: Beginner Skiers
  • Slope Angle: 5-25% slope gradient range (5-15 degrees)
  • Common Features: Majority groomed, few (if any) obstacles

Green circles indicate beginner slopes. They can be broken down into two broad categories. There are bunny slopes, or practice slopes, on one side and regular green slopes on the other. A bunny hill is a gentle slope that's usually separated from the main flow of skier traffic to create a better teaching environment.


On green slopes, you should be practicing stopping, turning, and speed control. You'll also use these mellow slopes to practice loading beginner ski lifts, which are slower and easier to manage. High-capacity lifts move fast, so it's best to practice loading and unloading on green lifts first.

Black and blue slope signs
Blue Square and Black Diamond slopes in Colorado. (Photo: Timo Holmquist of AlpInsider)

Blue Ski Slopes

  • Ability: Intermediate Skiers
  • Slope Angle: 25-45% slope gradient range (15-25 degrees)
  • Common Features: Some hazards like steeper pitches, well-spaced trees, moguls, and ungroomed terrain

Intermediate blue square slopes are steeper than greens and may feature obstacles. You could have small moguls or well-spaced trees to deal with. Also, not all intermediate slopes have been groomed. An ungroomed slope means the snow surface could be tougher to manage. 

Blues may have sections that are similar to greens. Theywill also have steeper sections that may not be visible from the top of the run. It’s important to read and trust the trail signs BEFORE committing to a ski run.

Black Ski Slopes

  • Ability Level: Advanced Skiers
  • Slope Angle: 45% gradient and higher (25 degrees and higher)
  • Common Features: Steep, likely ungroomed (though not always), unmarked hazards like tighter trees, large moguls, and multiple fall lines are possible

Anything harder than a blue intermediate slope is a black diamond. This level is for experienced skiers and means you are now flirting with the hardest runs on the mountain. The numeric scale (both percentage and degrees) gets a little crazy the higher you go, which is why most resorts consider more than 45% as an expert slope. 

Numerically, you can get as steep as 373% (75 degrees) before it's too steep for your skis to literally stay in contact with the ground. The Rambo run at Crested Butte Ski Resort in Colorado gets to ~143% (55 degrees) for a few hundred yards. Rambo is generally considered the steepest resort run in North America.

Two ski students stare at a Double Black Diamond EX sign at Beaver Creek Ski Resort. The signs explain that EX stands for Extreme terrain with numerous unmarked obstacles and hazards
My students stare at a Double EX sign at Beaver Creek Ski Resort. (Photo: Timo Holmquist of AlpInsider)

Double/Triple/Double EX Ratings Explained

  • Ability: Expert Skiers
  • Slope Angle: 45% and higher (25 degrees and higher)
  • Common Features: Expect some combination of ungroomed terrain, variable snow conditions, very steep maximum gradients, thick trees, moguls, small cliffs, exposed roots and rocks, tight corridors, couloirs, terrain traps, and more

In addition to steep pitches, double diamond runs could have any or all of the common features listed iabove. There are very few Triple Diamond Black runs, and because of individual resort classifications, they differ from place to place. A triple diamond at one place may be the same as a double diamond elsewhere. 

A Double Black Diamond EX is as close as you get to backcountry skiing within a resort. There will be a series of unavoidable hazards to deal with. The EX stands for Extreme, but even EX terrain is evaluated by ski patrol; in the backcountry, you’re on your own.

Doubles, Triples, and Black Diamond EXs are all expert slopes. They are dangerous and require your complete attention and skill.

Orange Ovals And Dotted Lines

On a ski map, you may notice orange ovals.

Those are terrain parks. A terrain park has man-made features, obstacles, and its own sets of rules that you need to follow to avoid injury. Terrain Parks are often fenced off from regular ski runs to reduce impact risk.

Dotted or dashed lines generally indicate a traverse or cut-through. In many cases, they follow the path of a summer road, which means they are thinner than many regular ski runs. They are often convenient but take note of the color. A black-dotted line will be harder to navigate than a green-dotted line.

How Are Ratings Different Overseas?

European and Japanese resorts follow a slightly different ski trail rating system than North America, New Zealand, and Australia. In the European ski trail rating system:

  • Blue trails are easy. 
  • Red trails are Intermediate trails
  • Black slopes are for experts.

Some areas also use Double and Triple Black slopes to mark the steepest terrain.

In some countries, Orange may be used to indicate an extremely-difficult slope. It’s similar to a Triple Diamond or Double Diamond EX rating. 

European resorts have also reclassified some black runs to yellow, with many of the features of EX terrain. It's important to study the ratings for whatever resort you visit, as things vary from country to country.

How Do You Know Your Ski Slope Rating?

Self-evaluation is always a good step. If it’s been a while and you’re unsure, start with green slopes and see how you feel. If you have trouble stopping, making turns, or loading ski lifts, stay on gentle terrain until you can master those skills.

To advance beyond blue slopes, you need to ski in a full parallel stance while staying in control. I also recommend learning how to use pole touches, making patterned turns all the way down a run and experimenting with bump or tree runs. Steeper, groomed blue runs are also great for carving.

One important thing to remember is that the ski slope levels are not weighted the same. The terrain variety on intermediate blue slopes dwarfs the variety on greens. In the same way, Black Diamond slopes are the most varied, and the differences between runs are often noticeable. There are difficult trails and easier trails within each ski slope color.

What To Do If The Ski Slope Becomes Too Difficult?

Before you get to the resort, go online and look at the ski trail map or download the resort´s ski app. Not only will you have a better understanding of the mountain, but ski patrol's number should also be listed there. 

When you get to the ski resort, take a second to read every big trail sign, paying special attention to the symbols next to the trail names.

If you happen to end up on a slope above your skill level, there are a few things you can do. You can always pull the ripcord and call ski patrol. Skier safety is why they’re there. And they would rather walk you out of a danger zone than have to treat a preventable injury. 

If you’re above the ski run, take your skis off and find another ski slope. If an easier slope isn’t available, walk back to the ski lift. Ski resorts will let you download the lift to avoid accidents. 

Unless you’re an expert, always go with friends. More people means more helping hands if you need to safely get down a steep slope. Have a buddy help carry your stuff while another helps guide you down. 

If you’re alone out there, ask a fellow resort guest for help or ask them to call ski patrol for you. NEVER try to push through a scary slope if you’re not ready; the injury risk is too high. One torn MCL or ACL is all it takes to end a ski season.


There you have it, the ski rating system for North America. It’s both simple and important to understand. There are three general categories (Green, Blue, and Black), and the system relies on slope steepness, obstacles, and natural hazards to calculate difficulty. Always start with gentle slopes and work your way up slowly to prevent accidents.

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*The information on this site is based on research and first-hand experience but should not be treated as medical advice. Before beginning any new activity, we recommend consulting with a physician, nutritionist or other relevant professional healthcare provider.