When you’re rock climbing or bouldering, knowing precisely how difficult a particular course is can be the difference between having a great time or being seriously exhausted and disappointed.

While the specific difficulty of any given climb is always somewhat subjective, there are rating systems that can help you choose a climb that will be an appropriate challenge for your skill. The climbing grade system we use in the US is called the Yosemite Decimal System, or YDS.

The YDS is a grading system used to rate the difficulty of climbs in rock climbing, mountaineering, and similar outdoor activities. The system was first developed in the 1950s at Yosemite National Park in California and has since become widely used around the world. It is not the only climb rating system, but it is the one most frequently used in North America.

The YDS has two scales. The first YDS scale is primarily used for hiking, and rates routes from 1–5. Routes rated 1–2 are hikes that won’t involve the use of your hands. Class 3 involves some scrambling. In the 4th class, hiking begins to turn into climbing. Once you reach the 5th class, you are getting to vertical or near vertical climbing. Beyond the basic class 5, climbing equipment becomes required.

The second scale measures climbs from 5.0 — 5.15, and further subdivides these climbs to let you know what technical skills you need to have before making an attempt. After the 5.10 difficulty, you will also see lettered divisions within these grades, like 5.10a or 5.11b.

The YDS also includes ratings for mountaineering and other types of climbing, but these are expressed in a different format than the rock climbing grades, using Roman numerals and other symbols.

If you’re climbing abroad, you should be familiar with other systems, including the French grading system, the UIAA grading system, and a handful of others.

While there are other grading systems, these five are the most commonly used. The chart below shows how these scales’ grades compare to each other. Not all levels of a particular scale have a direct comparison to all of the other scales.

In North America, bouldering problems use a different scale than climbing routes. The YDS does not apply to bouldering routes; instead, either the French Scale (usually referred to by its other name, the Fontainebleau Scale or Font Scale for short) or the Hueco V Scale is used.

The V Scale goes from 0 to 17 and may have a + or – for further specificity. These two scales are used interchangeably, so it’s useful to know how they correlate.

The V scale is even more subjective than the YDS for climbing routes. The concept is simple; the higher the number, the harder the problem. However, determining how hard a bouldering problem truly depends on the climber. This has caused controversy over how effective these ratings can be in some cases.

It is very important to understand the climbing grade ratings. Failing to do so and choosing a route that’s too difficult could end in serious injury or worse. But ratings can’t tell you everything about a route! Here are some key considerations about rock climbing grade ratings to keep in mind before choosing your next route.

Rock climbing grades are assigned by climbers who have completed the route, not an outside authority. This means that there are variations in difficulty based on personal experience and climbing style.

Additionally, grades can be influenced by outside factors. A 5.2 could easily become a 5.4 in bad weather. Route conditions like recent landslides or extra scree can make a route more challenging, too– and of course, individual fitness and experience impact your climbing ability. If you can normally complete a 5.11 but you’re recovering from an injury? Better ease your way back up to your higher grade.

The hardest move of a route determines the grade. This means it isn’t always a good estimation of overall difficulty. A climb with relatively easy moves but one really hard move will have the same grade as a climb with uniformly hard moves that match that one really hard move in difficulty.

Grades aren’t just subjectively assigned by climbers; they can even vary from one climbing area to another. In some places, you’ll see grades that feel inconsistent due to the local geography or the local climbing culture.

Grades aren’t consistent through time, either. As more climbers complete a route, their feedback may lead to the potential re-evaluation of the grade. Grades are almost always entirely determined through local consensus, so make sure to research your route to see if the grade has changed.

Grades can be helpful when you’re choosing a route, but they don’t tell you the whole story. Local geography plays an enormous role in how difficult a climb can be; as Sierra points out, local climbing styles may feel easy for the nearby community, but be much more difficult for somebody who’s never climbed in the area.

Route length, exposure, terrain, and equipment needed can also make a climb seem easier or harder. This is why it’s a great idea to climb with a partner who knows the route or to hire a guide who knows the terrain.

Climbing grades tell you how difficult a route is based on its most difficult move. What the grades cannot tell you is how dangerous the route actually is.

However, sometimes you will see a danger rating attached to a YDS number. This scale borrows its terminology from the movie industry.

This next part gets a little confusing. So far, we’ve used the term “grade” and “grade rating” interchangeably. This is standard practice and virtually every climber does it. However, when you’re researching a route, you may find that a YDS hike has a Roman numeral grade attached to its rating at the end. What’s that about?

This numeral is also referred to as a grade, and it indicates the time generally needed to complete a hike. Indoor climbs will never have this grade attached, since you won’t get stuck on a gym wall overnight. And unless you’re planning a multi-day expedition, it’s unlikely you’ll need to worry much about these grades. We’re including this chart for reference, and to explain what these grades are if you ever come across them.

Just like every other climbing grade, these grades are also subjective. Don’t push yourself to go too fast– if you need all day for a Grade I climb, then you need all day for a Grade I climb. It’s always better to be safe.

So now that you understand the different rock climbing grades, what’s the best way to use this knowledge? It really helps to have climbs to use for comparison. Knowing how some well-known climbs are graded can help you figure out where your abilities are as you choose your next climbing route. Here are some well-known climbs and their grades. If you haven’t done any of these, look up some routes that you have done to determine their grades.

Currently, Silence is the only 15.5d route anywhere in the world, and is considered the hardest climb on Earth.

We hope that this guide and the charts we’ve provided are helpful when planning your next climb. Remember to check with local guides and consider the climbing styles you’re used to, as well as safety when you’re planning a climb. After all, rock climbing grade ratings are a guide– not an objective set of rules!