Estimate calories burned on the trail using the MET formula. Based on ACSM Compendium of Physical Activities.
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This calculator is for reference only. Calorie estimates are based on MET values and may not account for individual metabolic rate, fitness level, or environmental conditions.
MET (Metabolic Equivalent of Task) is a measure of the energy cost of physical activities. One MET equals the energy expended while sitting quietly — approximately 1 kcal per kilogram of body weight per hour.
Activities are assigned a MET value relative to this baseline. Hiking on flat terrain has a MET of about 4.0, meaning it burns four times more energy than sitting. Steep mountain hiking can reach MET 8.0 or higher.
The formula used here
Calories = MET × body weight (kg) × time (hours)
This is the same formula used by sports scientists, physiotherapists, and fitness trackers worldwide.
Why your pack weight matters
Carrying a loaded pack significantly increases calorie burn beyond the simple extra weight. The body compensates for an unstable load on the back by engaging core and stabilising muscles continuously, increasing metabolic rate by 8–38% depending on load.
Research from the US Army Research Institute shows that a 15 kg pack increases oxygen consumption by approximately 25% compared to hiking with no load — even on flat terrain. On steep terrain, the effect is proportionally larger.
This is why long multi-day hikers consume 4,000–6,000 kcal per day, even without extraordinary exertion. The combination of distance, elevation, cold temperatures, and pack weight accumulates throughout the day.
On multi-day treks, pack weight reduces as food is consumed. Your calorie burn decreases slightly each day as the load lightens.
How to fuel your hike
A common rule of thumb: eat 200–300 kcal per hour of active hiking, starting from the first hour. Unlike cycling or running, hiking allows a more relaxed fuelling schedule — but multi-hour hikes still require consistent intake to maintain energy and prevent bonking.
Practical approach
Eat a proper meal 1–2 hours before. During the hike, consume 200–300 kcal per hour from portable sources — energy bars, nuts, dried fruit, or sandwiches. Drink water alongside eating, as dehydration accelerates fatigue.
On multi-day hikes, daily calorie needs typically reach 3,000–4,500 kcal depending on distance, elevation, and temperature. Cold weather adds 10–20% to requirements.
The MET formula gives a reasonable estimate — typically within ±15% of measured values for most hikers. Individual variation in fitness, walking efficiency, and metabolism means no calculator is perfectly accurate. Use the result as a planning guide, not an exact measurement. Wearable fitness trackers use similar MET-based calculations.
Why does body weight affect calories so much?
Heavier bodies require more energy to move. The MET formula multiplies by body weight because a 100 kg hiker and a 60 kg hiker doing the same activity expend very different amounts of energy — the heavier person burns approximately 67% more calories per hour at the same pace.
Does altitude affect calorie burn?
Yes, but the calculator does not account for altitude. At elevation above 2,500m, reduced oxygen availability forces the body to work harder, increasing calorie burn by roughly 5–15% compared to sea level. For high-altitude treks (Alps, Himalaya), add 10% to the result.
How does this compare to a fitness tracker?
Most wearable trackers use a similar MET-based formula combined with heart rate data. Heart rate adjustment can improve accuracy by 5–10%, but requires measuring it during the hike. For planning purposes, the results should be comparable to your watch's estimates.
Are calories different going uphill vs downhill?
Yes. Uphill hiking burns significantly more calories than flat or downhill. Downhill hiking burns fewer calories per km but is harder on the knees and uses different muscles. This calculator accounts for elevation gain (uphill effort) but does not subtract for descents — giving a conservative estimate for the full hike.
What is a typical calorie burn for a day hike?
A typical half-day hike (3–4 hours, 10–15 km, moderate terrain) burns 800–1,500 kcal for a 70–80 kg hiker with a light pack. A full mountain day with 1,000m of climbing can reach 2,000–3,000 kcal. These are significant numbers that explain why you feel hungry after a long hike.
Should I eat back all the calories I burn?
For single day hikes, most people don't need to eat back all burned calories — the body has glycogen and fat reserves. However, on multi-day hikes, consistent calorie replacement is important to maintain energy and recover overnight. Under-fuelling on long treks leads to fatigue, poor judgement, and increased injury risk.
How does cold weather affect calorie needs?
Cold weather increases calorie burn in two ways: the body burns extra energy maintaining core temperature (thermogenesis), and heavy clothing increases the energy cost of movement. In temperatures below 0°C, add approximately 10–20% to the calculated result. Winter mountaineering can require 5,000+ kcal per day.