MET values and how they estimate hiking calories
What a MET is, which hiking effort levels map to which numbers, and why terrain and pack weight change the calories you burn.
What a MET actually is
MET stands for metabolic equivalent of task, a way to describe how hard an activity is compared with sitting still. One MET is your resting energy use, roughly one kilocalorie per kilogram of body weight per hour. An activity rated at 6 MET burns about six times that resting rate. Because the scale is anchored to body weight and time, multiplying MET by kilograms by hours gives a clean calorie estimate without needing a heart rate monitor or lab equipment.
Matching effort to a number
This calculator offers four presets that cover most day hikes. Easy walk at 4 MET suits flat, relaxed strolling on smooth ground. General hiking at 6 MET fits typical trail walking with mild ups and downs. Hilly or pack at 7 MET reflects rougher terrain or carrying a loaded backpack. Steep climb at 8 MET covers sustained uphill effort. Choosing the preset that best matches your day is the single biggest lever on the accuracy of the estimate.
Why weight and time drive the total
Two hikers on the same trail can burn very different amounts. A heavier person moves more mass against gravity, so their calorie burn scales directly with body weight in the formula. Time matters just as much, since energy use accumulates every hour you keep moving. That is why the tool asks for both, and why doubling either your weight or your hours roughly doubles the calories reported, with the MET value setting the intensity of each of those hours.
What the formula leaves out
A single MET value cannot capture everything. Steep grade, a heavy or poorly balanced pack, loose or muddy footing, thin air at altitude, temperature, and your own fitness all shift real energy use up or down. The MET presets bake in a rough average for terrain, but they do not adjust for a 20 kilogram pack or a scramble over boulders. Use the number to plan food and water, then listen to your body on the trail rather than treating the figure as exact.