Japan Mountain and Hike Grading
Japan has a grading system for mountain trails, created by civic groups trying to standardize an expression of the level of difficulty for the many, many trails nationwide.
The purpose of a grading system is to allow hikers and climbers to match their fitness with the trail, so that accidents can be avoided. It’s true that a lot of hiking and climbing guidebooks, or Internet sites, have simple gradings like “beginner”, “intermediate” and “expert”, but those subjective gradings differ from place to place, by grader, and even from route to route up the same mountain.
On the other hand, with a more objective grading system, which is the same from region to region or for different routes up the same mountain, triers can more safely plan their hikes and ascents.
Grading Calculation
Grading has two aspects: “Physical Stamina” and “Technical Difficulty”.
Physical Stamina
The stamina level needed for a trek is derived from the “route factor” (also “course factor”), which is calculated from the following four aspects:
- Standard course time (without breaks)
- Route length
- Accumulated elevation gain
- Accumulated elevation drop
The formula for route factor is as follows:
(Standard course time hours x 1.8) + (route length km x 0.3) + (elevation gain km x 10) + (elevation loss km x 0.6)
From the calculated route factor, the stamina level can be estimated from 1 to 10, with 1 being the easiest, and 10 the hardest.
| Stamina Level | Route Factor | № Nights |
|---|---|---|
| 1 | <10 | 0 (day trip) |
| 2 | 10-20 | |
| 3 | 20-30 | |
| 4 | 30-40 | 1+ |
| 5 | 40-50 | |
| 6 | 50-60 | 1-2+ |
| 7 | 60-70 | |
| 8 | 70-80 | 2-3+ |
| 9 | 80-90 | |
| 10 | >90 |
Example 1 - a hike that requires 6 hours, is 8.2km in length, has 930 m elevation gain and 920 m elevation loss would be calculated as:
6×1.8＋8.2×0.3＋0.93×10＋0.92×0.6＝23.112
… rounding up to a route factor of 24, and therefore a stamina level of 3, so day trip is possible.
Example 2 - a hike that requires 11.5 hours, is 23km in length, ascends and descends 2400m would be:
11.5×1.8＋23×0.3＋2.4×10＋2.4×0.6＝53.04
… rounding up to a route factor of 54, for a stamina level of 6, and needing 1 or 2 nights.
On top of that, you can easily calculate calories and water needed for the trek using this equation:
route factor x (body weight in kg + pack weight in kg)
A trek with route factor 30, for a 90kg person carrying 10kg of equipment is:
30 x (90 + 10) = 3000
… which means 3000 kCal of energy and 3000 mL (3L) of water. However, this is just a rule of thumb estimate, and care should be taken to adjust for personal and route differences.
Technical Difficulty
Considering mountain route conditions, the following table sets out five ranks of technical difficulty for triers to complete a route, designating with letters from A through E, and ranked from easiest to most difficult.
| Technical Difficulty Level | Mountain Route Condition | Techniques or Skills Required |
|---|---|---|
| A | - Well maintained - Even if you trip, there is low risk of a plunge or slide - No worry about becoming lost |
- Basic hiking gear |
| B | - Passing valleys and cliffs with possible snow - Sudden ups and downs - Path sometimes hard to follow - Areas where if you trip, there is a risk of plunge or slide accidents |
- Mountain trekking experience needed - Map reading and orienteering knowledge is preferred |
| C | - Areas with ladders and chains (via ferrata), with snow, or where fording a stream is needed - Mistakes mean dangerous falls or slides - Includes places with insufficient or no trail markers |
- Map reading and orienteering - Sufficient physical fitness to pass through areas with chains and ladders |
| D | - Difficult rock ridges, scree fields, via ferrata, overgrown areas to navigate, areas with snow or where stream fording is required - Steep ascents or descents that require use of hands - Areas with ladders and chains or limited artificial assistance such as signage, where falls or slides are a significant risk |
- Map reading and orienteering, route-finding skills - Sufficient physical fitness and skill to keep balance while passing through areas with chains and ladders, over rocks or snow |
| E | - Areas with continuing ups and downs along cliffs or tricky rock ridges, where there is repeated risk of falls or slips - Continued areas where navigating deep overgrowth is needed |
- Map reading and orienteering, advanced route-finding and decision-making skills - Sufficient physical fitness and skill to keep balance while passing through areas with chains and ladders, over rocks or snow - Dangerous areas where rope work is required |
Regarding how to rank from the standpoint of technical difficulty, the route is ranked by its most difficult area. For instance, even if a route could be given an A rank at first, if there are ladders and chains to navigate later, it is ranked overall as a C.