The difficulty of ice climbing is determined by experienced climbers during their first ascent, using permanent Alpine climbing routes that do not change with seasons or time as reference. The traditional difficulty grading system uses the Scottish difficulty scale, which is divided into 7 levels:

Grade 1: Short climbing routes with moderate snow and ice slopes, less than 50 degrees in steepness;

Grade 2: Longer climbing routes with snow and ice slopes steeper than 50 degrees, featuring some ice, snow, or rock steps in certain sections;

Grade 3: Longer climbing routes with some sections approaching 90 degrees in steepness;

Grade 4: Long climbing routes on near-vertical 90-degree ice walls, quite challenging, with some mixed climbing sections possible;

Grade 5: Very long climbing routes, almost entirely on near-vertical 90-degree ice walls, with many difficult sections and numerous mixed climbing terrains;

Grade 6: Long climbing routes, mostly on permanent Alpine ice walls and mixed climbing, extremely difficult;

Grade 7: High-altitude mountain areas such as the Himalayas and remote, unexplored regions. Climbing routes are long, with very high difficulty and danger.

American mountaineer Jeff Lowe further classified these 7 grades into permanent ice walls and seasonal ice walls.

AI stands for permanent ice walls

WI stands for seasonal ice walls

When climbers see either of these two symbols, they know whether they will be climbing a seasonal or permanent ice wall.

Although there are difficulty grades for ice climbing, the actual difficulty can vary with the season and weather. Conditions on the ice wall often change, so each climber should consider adding one extra level of difficulty when assessing the climb to ensure a successful ascent.

Finally, ice climbing enthusiasts are advised to carefully gather information about the ice wall they plan to climb before heading out. Always be bold yet cautious, and avoid arrogance or impatience when ice climbing.

The Sierra Club in the United States established the following grades early on to facilitate the description of climbing route difficulties:

Grade 1: Walking on rocky slopes, generally without needing hand support for balance

Grade 2: Sometimes using hands, but beginners and less agile individuals do not need ropes for protection

Grade 3: Falling poses considerable danger, hands are frequently used, and it's best to have a rope ready

Grade 4: Requires certain climbing techniques; most believe that since falls can be life-threatening, a rope is necessary. Protection is generally available, and protection points are easy to find.

Grade 5: Ropes and protection are mandatory to prevent serious consequences from falls; varying degrees of special climbing and protection techniques are required. From this grade onward, it is called "technical climbing."

Grade 5 was originally divided into 10 sub-levels based on difficulty, known as the "Yosemite Decimal System" (YDS, Yosemite also translated as "Yosemite"), in the format of "5.0", "5.1", "5.2"... up to "5.10". By definition, anything above 5.10 is Grade 6, requiring direct use of artificial aids for climbing. However, with advancements in climbing techniques and equipment (climbing shoes, chalk), the YDS became an open-ended scale, leading to subdivisions like "5.11". After 5.10, each numerical grade is further divided into four sub-letter grades: a, b, c, and d. Currently, the hardest routes in the world are around 5.14c or 5.14d. The difficulty of new routes is initially estimated by climbers based on their subjective experience with previously climbed routes (highly subjective), then gradually becomes fixed as more people climb it. For example, when the highest grade was still 5.10, someone climbed a new route and felt it was more difficult than the gap between 5.10 and 5.9, so they had to break the artificially set Grade 5 limit and call it 5.11.

Generally speaking, untrained individuals can handle up to 5.6, those with basic technical training can manage 5.6–5.9, and starting from 5.10, regular technical and strength training is required. But this is a very generalized statement.

The YDS grades routes based on the hardest "technical move" on the route. A route with ten 5.10 moves and one with only one 5.10 move near the ground are both rated 5.10. Also, the grades of different types of routes (slabs, cracks, friction) are sometimes hard to compare. However, as more people climb them, the grades become more objective and strict. The UK, France, Germany, and Australia have their own grading systems. The UK grading combines technical difficulty and risk.

With strict grading, route selection and training for improvement become easier. But chasing numerical grades makes climbing less enjoyable. However, that’s a matter of personal preference.