What Is the Route Constant? The Formula for Hiking Calorie Burn and How to Use It
Two “5-hour courses” can feel completely different and take very different amounts of energy if one is mostly flat and the other is one steep climb after another. The route constant, devised by Masayoshi Yamamoto of the National Institute of Fitness and Sports in Kanoya, Japan, expresses that difficulty as a single number. This article explains the route constant formula and what each term means, how to get calorie burn from your body weight and pack weight, calculations for example courses, what the size of the number tells you, and how many kcal you save by lightening your pack.
The route constant is a number for how “hard” a hiking course is
The route constant is a number that expresses how demanding a hiking course itself is. It adds up four factors, walking time, distance, total ascent and total descent, each weighted according to how much load it puts on the body. Because it does not include the hiker's body weight or pack weight, you can compare courses directly: “this course is so many times harder than that one”.
Note that elevation goes in as kilometres, not metres. A total ascent of 1,000 m is 1.0, and 450 m is 0.45. For course time, use the standard course time given on hiking maps (excluding breaks). The point is to use the time set for the course, not how long it actually took you, so that courses can be compared on the same basis.
What the four terms represent
| Term | Coefficient | Meaning |
|---|---|---|
| Course time | 1.8 | The load of walking continuously; rises with time |
| Distance walked | 0.3 | The load of moving horizontally; rises with distance even on flat ground |
| Total ascent | 10.0 | The load of lifting the body; the heaviest of the four |
| Total descent | 0.6 | The load of braking on the way down; much smaller than ascent |
The standout feature is the ascent coefficient of 10.0. A 1,000 m climb is equivalent to about 5.6 hours of course time (10 ÷ 1.8). Even between courses with the same distance and time, the more height you gain, the larger the route constant.
“Total ascent” is not the height difference between the trailhead and the summit but the sum of every climb along the way. On a traverse over several minor peaks it can be much larger than the trailhead-to-summit difference. Hiking map apps and GPS apps often list it in the course information as “total ascent and descent”, so use those figures.
Calculating the route constant for example courses
| Example course | Calculation | Route constant |
|---|---|---|
| Low-mountain hike (3 h, 7 km, 450 m up and down) | 5.4 + 2.1 + 4.5 + 0.27 | 12.3 |
| Intermediate day hike (5 h, 10 km, 1,000 m up and down) | 9.0 + 3.0 + 10.0 + 0.6 | 22.6 |
| Long day hike (8 h, 16 km, 1,600 m up and down) | 14.4 + 4.8 + 16.0 + 0.96 | 36.2 |
| Ascent only (3.5 h, 5 km, 900 m up, ropeway down) | 6.3 + 1.5 + 9.0 + 0 | 16.8 |
The intermediate day hike (22.6) is about 1.8 times as hard as the low-mountain hike (12.3), and the long day hike (36.2) is about 3 times as hard. Taking the ropeway down not only shortens the walking time but also removes the descent term, so even with a 900 m climb the route constant stays at 16.8.
The tool labels the size of the route constant as follows: under 10 is “light (walks, low-mountain hikes)”, 10–20 is “moderate (low to intermediate day hikes)”, 20–30 is “fairly hard (day hikes with about 1,000 m of climbing)”, 30–40 is “hard (long day hikes, the first day of a hut trip)”, and 40 or more is “very hard”. These bands are the tool's own guide, so it is best to compare against the route constants of courses you have walked before.
Calorie burn = route constant × (body weight + pack weight)
Multiply the route constant by “body weight + pack weight (kg)” and you get an estimate of the energy (kcal) used to walk the course. The idea is that the heavier the load you carry, the more energy the same course takes.
| Course (route constant) | 50 kg body + 6 kg pack | 60 kg body + 7 kg pack | 70 kg body + 9 kg pack |
|---|---|---|---|
| Low-mountain hike (12.3) | About 690 kcal | About 820 kcal | About 970 kcal |
| Intermediate day hike (22.6) | About 1,270 kcal | About 1,510 kcal | About 1,790 kcal |
| Long day hike (36.2) | About 2,030 kcal | About 2,420 kcal | About 2,860 kcal |
| Ascent only (16.8) | About 940 kcal | About 1,130 kcal | About 1,330 kcal |
A 60 kg person walking the intermediate course uses about 1,510 kcal, more than six bowls of rice (about 240 kcal each). A long day hike goes over 2,000 kcal and can exceed a day's basal metabolism. How much of this energy to replace by eating on the trail is calculated in the trail food article.
Using the route constant to choose mountains and prepare
- 1
Work out the route constant of courses you have walked
Calculate courses that felt easy and ones that felt hard, and find the number that is “just right” for you.
- 2
Compare with your next course
A course well above your previous maximum is likely to be too much physically. Raising the number gradually gives you a guide for stepping up.
- 3
Decide on trail food from the calorie burn
Multiply by body weight plus pack weight to get the energy used, and decide how much to eat while walking.
- 4
Work out water with a separate formula
The route constant is for calculating energy. Water is calculated as “body weight × walking time × 5” (the water amount article).
In the hiking water and trail food calculator, enter the course time, distance and total ascent and descent, and it shows the route constant and a difficulty guide, then calculates the energy used from your body weight and pack weight in one go. If you do not know the course time, it can also estimate it from distance and elevation (how to estimate course time).
FAQ
- Do I enter elevation in metres for the route constant?
- Convert it to kilometres. A total ascent of 1,000 m is 1.0, and 650 m is 0.65. If you enter metres, the ascent term becomes 1,000 times too large.
- Is the course time the time I actually walked?
- The route constant uses the standard course time given on hiking maps (excluding breaks), so that courses are compared on the same basis. Your own pace comes in when you plan water and breaks.
- What is a typical route constant?
- A low-mountain hike of about 3 hours is around 10 to 13, and a 5-hour day hike with about 1,000 m of climbing is around 20 to 25. The tool calls 20 to 30 “fairly hard” and 30 to 40 “hard”. Comparing with courses you have walked before is the most reliable approach.
- Why is the descent coefficient so small?
- On the way down you do not have to lift your body, so much less energy is used than on the way up. Descents, however, put heavy impact on the muscles and knees and make falls more likely, so being easier in energy terms does not mean they are less tiring.
- How do I calculate for a hut trip?
- Calculate the route constant and energy used for each day separately. If you calculate two days together, you cannot tell how much to eat on each day.
Tools in this article
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