Energy Miles
How we calculate event diffuculty
Energy Miles (EM) are our unit for describing how demanding an outing is. Rather than relying on distance alone—which ignores elevation—or elevation alone—which ignores the sport—we combine both with a per-sport effort multiplier. This way, a 10 km climb is correctly flagged as tougher than a 10 km riverside stroll.
The formula stems from Paul Petzoldt, a mountaineer and founder of the National Outdoor Leadership School. In his 1976 book Teton Trails, he proposed that one energy mile equals the energy required to walk one mile on flat terrain, with two extra energy miles added for every 1,000 feet of elevation gain. So one mile climbing 1,000 feet costs about three energy miles.
Beyond the default Energy Mile (designed for hiking), we've added a sport multiplier that accounts for the difficulty and expected energy use of different activities. This lets us use a single unit across all sports. We map every event's total EM score to a named difficulty tier, from Easy through Extreme.
These indicators are by no means perfect—difficulty is subjective to each person. But we aim to make an educated guess, so you have a useful estimate going in.
The formula
EM = ((km × 0.621) + (m × 3.28 ÷ 500)) × sport multiplier
- km
- distance travelled, in kilometres
- m
- total elevation gain, in metres
- 0.621
- kilometre → mile factor (the unit origin of "miles")
- 3.28 ÷ 500
- metres → feet, divided by 500 ft — so every ~500 ft of climb counts as roughly one extra mile of effort
Worked example: 1 km of distance plus 100 m of climb works out to
1.28 EM
before the sport multiplier is applied.
Difficulty tiers
The total EM score for an event is matched against these thresholds in order; the first tier whose upper bound (max EM) is not exceeded wins.
| Tier | Range |
|---|---|
| Easy | up to 7 EM |
| Moderate | 7–13 EM |
| Challenging | 13–18 EM |
| Difficult | 18–23 EM |
| Very Difficult | 23–27 EM |
| Extreme | 27+ EM |
Sport multipliers
Each sport carries its own effort multiplier — a 1.0 multiplier means "baseline hiking effort", below 1.0 is easier per km, above 1.0 is harder. The worked example below is always 1 km + 100 m climb (1.28 EM at baseline), so you can compare sports side-by-side.
| Sport | Multiplier | Example EM |
|---|---|---|
| Hiking | × 1.00 | 1.28 EM |
| Biking | × 0.40 | 0.51 EM |
| Orienteering | × 1.20 | 1.53 EM |
| Canoeing | × 0.60 | 0.77 EM |
| Swimming | × 3.00 | 3.83 EM |
| Snowshoeing | × 1.35 | 1.72 EM |
| Climbing | × 3.50 | 4.47 EM |