The most rational grading system is that of Canada and France. This system is used in Canada and the Alps, which together account for roughly three-quarters of ice climbing activities worldwide. American climbers like Jeff Lowe also use this grading system. It consists of two numbers, such as II-5.
The first number (Roman numeral) indicates "seriousness." It represents remoteness, climb length, descent difficulty, hazard level, and route continuity. "I" refers to a single pitch by the roadside, whereas "VI" requires extensive alpine climbing experience, and unless you're a top-tier climber moving very quickly, an overnight bivouac is almost inevitable.
The second number (Arabic numeral) indicates "technical grade," representing the technical difficulty of the hardest part of the route. Verticality, protection ease, type of ice, and pitch continuity are also taken into account. "2" means using only one ice tool; to my knowledge, currently there are only a few vertical or nearly vertical routes without protection, or massive overhangs that are rated as Grade "7." Since this is similar to the American WI system, this technical grade is also denoted as "WI," so the WI system is essentially akin to the technical grade.
This system contains quite a lot of information because it uses two different types of difficulty grading, yet the two are not entirely unrelated—in other words, technically easier routes generally also require less effort. (Because you can often descend.)
Difficulty Levels:
Grade I: Short climbs by the roadside, with safe protection and easy descent.
Grade II: One to two pitches, in easily accessible areas, slightly hazardous, with easy downclimbing or rappelling.
Grade III: Low-altitude locations, several pitches, may take several hours; or require walking or skiing some distance, needing good cold-weather travel skills; or occasional objective hazards; usually involves rappelling down.
Grade IV: High-altitude multi-pitch climbs or in remote areas, requiring mountaineering and cold-weather skills, potential for avalanches or rockfall, more difficult descent possibly involving artificial anchors.
Grade V: Alpine walls, long climbs, requiring high ability and commitment, exposure to avalanches or severe weather, possibly involving long and difficult descents.
Grade VI: Alpine walls, multi-pitch, only top climbers can complete in a day, may involve cold alpine logistical challenges.
Grade VII: The largest and most difficult Himalayan-style alpine climbs (per Jeff Lowe’s definition).
The Scottish ice climbing grading system is also related to technical grade (1 to 7), assessing the hardest pitch, including the types of climbing encountered, ice thickness, and ice features such as stalactites, mushrooms, or overhanging walls.
Grade Difficulty:
Grade I: Can be walked up wearing crampons only.
Grade II: Single pitch of 60–70-degree ice, includes short steep steps, with safe protection.
Grade III: Continuous 70–80-degree ice, usually thick and hard, may contain short steep sections but with good resting points, and safe protection.
Grade IV: Continuous 75–85-degree ice, good resting zones are sparse, with some significant vertical sections, usually good ice quality offering reliable protection.
Grade V: Many challenging pitches of 85–90-degree ice, requiring skills and ability similar to 5.9 in rock climbing.
Grade VI: Very steep, with few rest opportunities, often requires hanging belays, ice quality not optimal, safety questionable, demands high skill, roughly equivalent to 5.10 in rock climbing.
Grade VII: Nearly vertical ice walls, very thin, poor ice quality, uncertain if attached to rock, protection difficult or impossible, requiring approximately 5.12-level professional skills.
Reprinted from Shenzhen Mountaineering & Exploration Magazine
Introduction to Ice Climbing Grades
Ice climbing difficulty is determined by experienced climbers after the first ascent, using permanent alpine climbing routes unaffected by season or time as reference. The traditional grading system adopts the Scottish Difficulty System, divided into 7 grades:
Grade 1 Difficulty: Short climbing routes, moderately difficult snow/ice slopes, with gradients under 50 degrees.
Grade 2 Difficulty: Longer climbing routes, snow/ice slopes over 50 degrees, with some sections featuring ice, snow, or rock steps.
Grade 3 Difficulty: Longer climbing routes, with some sections approaching 90-degree gradients.
Grade 4 Difficulty: 90-degree vertical ice wall routes are longer, more challenging to climb, and some sections may also involve mixed climbing.
Grade 5 Difficulty: The climbing route is very long, almost entirely composed of 90-degree vertical ice walls, with numerous difficult sections, many of which involve mixed climbing terrain.
Grade 6 Difficulty: The climbing route is long and mostly consists of alpine permanent ice walls and mixed climbing, making it extremely difficult.
Grade 7 Difficulty: Found in high-altitude mountain regions like the Himalayas and remote, unexplored areas. The climbing routes are long, with very high difficulty and significant danger.
American mountaineer Jeff Lowe further categorized these 7 grades into permanent ice walls and seasonal ice walls. AI stands for permanent ice walls, and WI for seasonal ice walls. When climbers see either of these symbols, they understand whether they will be climbing a seasonal or permanent ice wall.
Although ice climbing has difficulty grades, the actual difficulty can vary depending on the season and weather conditions.
The condition of ice walls often changes, so every climber should consider adding one extra level of difficulty when assessing ice climbing routes to ensure a successful ascent.
Finally, ice climbing enthusiasts are advised to carefully gather information about the ice wall they plan to climb. Always be bold yet cautious, and avoid arrogance or impatience.
Snow-Ice-Rock Mixed Sections (M1 - M8) Compiled by Zhang Zhongshu and Qiu Zihuan
These are a generalization of the established system for rating ice described above. There is no consensus. However, in the method which seems somewhat dominant in Colorado (home of the most desperate mixed climbs, probably due to lack of ice :-)) and championed by Jeff Lowe, the letter "M" is added to the technical grade. An "M5" is supposed to be as hard as a "5" in pure ice (the equivalence is obviously hard to establish) but involves dry-tooling and similar maneuvers. Sometimes, the grade is detailed into the pure ice part and the mixed part, i.e., Octopussy is "M8 WI5" since there are extreme dry-tooling moves to reach the free-hanging stalactite, but once established on it, the ice is not that hard. However, usually, the latter part will be omitted since it is not the crux, leaving only "M8". The global rating could read something like an algebraic formula: "II M8 WI5 X" (X in my opinion: I think all the free-hanging stuff can easily collapse, as some climbers have experienced in the early 90s. I would be cautious with the current fad for this sort of climbing).
This is a generalization of the system described above, and there is no consensus. However, this method seems mainly used in Colorado (where mixed climbing is popular, probably due to a lack of ice :-)) and is supported by Jeff Lowe. The letter "M" is added before the technical grade. An "M5" is considered as hard as a pure ice "5" (in terms of difficulty), but includes dry-tooling and similar techniques. Sometimes, the grade is broken down into the pure ice part and the mixed part—for example, Octopussy is "M8 WI5" because the extreme dry-tooling moves to reach the free-hanging stalactite are very difficult, but once on the ice, it’s not that hard. However, the latter part is usually omitted because it’s not the crux, leaving just "M8." The overall grade might look like an algebraic formula: "II M8 WI5 X" (X, in my opinion, means I think all the free-hanging parts could easily collapse, as some climbers experienced in the early 90s. I’d be cautious about the current trend for this type of climbing).
Another way to rate mixed climbs is to assign a rock-climbing grade to the rock moves. This method is preferred by Canadians, who seem somewhat skeptical about all the M9 climbs :-). The issue is that you’re using ice-climbing gear, so the grade is usually not "absolute" but relative to how it feels with crampons—thus easier than a normal rock grade. But again, there’s no real consensus on this. (from Quang-Tau Luong)
Another method to assess mixed climbing grades is to evaluate the rock-climbing portion. This approach is more commonly used by Canadians, who tend to be somewhat doubtful about all M9-rated routes :-). The issue is that you’re using ice-climbing equipment, so the grading isn’t "absolute" but rather relative to how it feels with crampons, making it easier than a standard rock grade. Still, there's no universal agreement on this.
Snow-ice-rock mixed climbing is primarily a mix of ice and rock, or dry-tooling (climbing rock with ice tools and crampons). The difficulty is determined relative to either pure ice walls or rock climbing, and as you can imagine, drawing a direct comparison between the two is quite challenging—so only relative comparisons can be made.
Appendix
Comments on the Ice Rating System (from Quang-Tau Luong)
Comments on Ice Climbing Routes
Although Albi Sole refers to Grade 5 as the "5.9 of ice climbing," don't kid yourself. A Grade 5 lead is a quite serious undertaking—in my opinion, more comparable to a 5.10 trad lead. I am one of the only people I know (:-)) who has been able to lead Grade 6 ice while being only a 5.10- climber. You’ll find that Grade 5 ice routes are actually quite rare. For example, a guidebook like the one for Western Ontario or Western British Columbia is 140 pages long but lists only a handful of Grade 5 climbs. There are no Grade 6 routes at all in well-established areas like New England, Ontario, or British Columbia (well, I must say, until 1996, when The Theft was climbed in BC). This is because a Grade 5 climb needs to have about a half-pitch of vertical ice, and a Grade 6 needs a full pitch of vertical ice—which brings me to the second point. Vertical means 90 degrees, not 85 degrees. This seemingly minor difference is actually quite important. When you’re on 85-degree ice, you might feel like it’s overhanging due to your body position, but in reality, there aren’t many formations that are strictly vertical, except for free-standing columns.
Although Albi Sole considers Grade 5 to be the "5.9 of ice climbing," don't be fooled. Leading a Grade 5 is a serious challenge—in my view, it’s more like a traditional 5.10 lead. I’m one of the few people I know (:-)) who has led Grade 6 ice while only being a 5.10- climber. You’ll notice that Grade 5 ice routes are actually quite hard to find. For instance, a guidebook such as the one for Western Ontario or Western British Columbia spans 140 pages but lists only a few Grade 5 climbs. There are no Grade 6 routes at all in well-known areas like New England, Ontario, or British Columbia (well, until 1996, when The Theft was climbed in BC). This is because Grade 5 routes require about half a pitch of vertical ice, while Grade 6 requires a full pitch. That brings me to my next point: vertical means 90 degrees, not 85. This small difference is actually quite significant. When you're on 85-degree ice, it might feel overhanging because of your stance, but there are very few formations that are truly vertical, except for free-standing columns.
To the best of my knowledge, there are only a handful of Grade 7 pure ice climbs in the world:
As far as I know, there are only a few Grade 7 pure ice climbing routes in the world, as follows:
Riptide and Gimme Shelter (Canadian Rockies) were among the first established (mid-1980s). Gimme Shelter remains unrepeatable because it has never fully reformed.
La Massue and La Lyre, both at Fer de Cheval (Northern Alps), were established on the same day in December 1991.
Sea of Vapors (Canadian Rockies), winter 1993 (7+)
Apart from those, there are a few one-pitch mixed climbs that have been given a Grade 7. T. Renault in France (Laventure, c’est laventure, next to Glacenost in the Northern Alps, France) and J. Lowe in the US (Terriebel Traverse, Seventh Tentacle, Octopussy 8??, in Vail, CO) are the creators. While Thierry was climbing "Laventure, c’est laventure," the chunk of ice beneath him collapsed, and he had to do a one-arm pull-up that he didn’t think he could manage. Jeff’s climbs involve free-hanging stalactites reached via a dry traverse, protected on the rock and with a pre-placed screw, as I’ve heard. The second ascent team mentioned that one of the climbs was overrated. The first Grade 6 climb in the world might have been Bridalveil Falls in Telluride in the mid-1970s. In the Alps, it was Les Viollins, although the first ascent—solo by Chantriaux in 1982—is somewhat controversial.