Article — Hiking Calorie Calculator
Hiking Calorie Calculator: Trail Energy and Time
A 70 kg adult burns roughly 400-500 kcal per hour hiking moderate trail at 4 km/h, climbing 600 m, and 700-900 kcal on steep terrain. This hiking calorie calculator uses Ainsworth Compendium MET values plus a Naismith-style time model to estimate both numbers from your weight, distance, elevation gain, and pace.
Calorie burn on a hike scales with three things: body weight (linear), time on the trail (linear), and the MET value of the terrain. Distance alone tells you almost nothing - 8 km on a flat rail-trail at 5 km/h burns about half the calories of 8 km up a rocky 12% grade.
What the hiking calculator does
The tool takes four inputs you can measure or look up on a trail app: body weight, distance, elevation gain, and your typical flat-ground pace. You pick a terrain category and the calculator returns three numbers - calories burned, total time, and the effective MET. Pace acts as your personal fitness anchor; a fit hiker who walks 5.5 km/h on flat moves faster on the climb than someone whose flat pace is 4.0 km/h.
The two ingredients of the calorie number are MET and time. The MET is set by terrain and adjusted up by 0.15 for every percentage point of grade above 2%. The time uses your flat pace for the horizontal distance, then adds one hour for every 600 m of climbing.
The original Naismith rule, published by Scottish climber William Naismith in 1892, gave one extra hour per 2,000 feet of ascent at a flat pace of 3 mph. The metric equivalent - 600 m of climb per added hour at 4.8 km/h - is still the default in mountain rescue planning across the UK and Alps.
The hiking calorie formula
Every MET-based calorie estimate uses the same equation:
kcal = MET x body weight (kg) x time (hours)1 MET = 1 kcal/kg/hour at restWorked example. You weigh 70 kg, hike 10 km of rolling trail (MET 6.0) at a base pace of 4.8 km/h. The flat-time portion is 10 / 4.8 = 2.08 hours, the climb adds 500 m / 600 = 0.83 hours, total 2.9 hours. Calories: 6.0 x 70 x 2.9 = 1,218 kcal. The same hike at 90 kg jumps to 1,566 kcal - body weight is linear, so a 30% heavier hiker burns 30% more.
MET values for hiking
The MET values used here come from the Compendium of Physical Activities (Ainsworth et al.), the same source the American College of Sports Medicine uses for activity energy expenditure. Hiking codes 17080-17087 cover the range from flat trail to scrambling.
- Flat / graded trail: 4.5 MET. Park paths, rail-trails, fire roads.
- Rolling hills (3-6%): 6.0 MET. Most maintained day-hike loops.
- Hilly (7-12%): 7.3 MET. Sustained climbs, switchbacks, talus.
- Steep (13-20%): 8.5 MET. Approach trails, alpine ascents.
- Very steep / scrambling (20%+): 10.5 MET. Class 2-3 routes.
- Backpacking, cross-country: 7.8 MET. Off-trail with a pack.
Hiking time and Naismith's rule
Time is harder than calories because it depends on personal fitness. The Naismith rule treats horizontal motion and vertical motion as separable - you spend distance / pace on the flat part and elevation / 600 m on the climb. Mountain guides usually multiply the result by a terrain factor: 1.0 for groomed trail, 1.1-1.2 for rough or rocky ground, 1.3-1.4 for off-trail or scrambling.
Pack weight and hiking burn
A loaded backpack adds calorie burn in proportion to its weight relative to your body weight. Field studies cited by the American College of Sports Medicine put the premium at roughly 8-10% per 11 kg (25 lb) of pack. A simple approximation is to add your pack weight to your body weight before running the calculation - a 70 kg hiker with a 14 kg overnight pack should plug in 84 kg.
If you weigh your pack at the trailhead, log it once and reuse it. Ultralight packs (under 7 kg fully loaded for 2-3 days) shave 50-150 kcal per hour of hiking compared with a 16 kg traditional load.
Elevation, grade, and hiking pace
Pace falls roughly linearly with grade. Each percentage point of sustained climbing costs about 0.15-0.20 km/h off flat pace. A hiker who cruises at 5 km/h on flat ground holds about 3.5 km/h on a 10% grade and 2.5 km/h on 20%. Above 2,400 m (8,000 ft), thinner air subtracts another 5-15% from pace - factor this in for alpine routes by lowering your input pace, not by adjusting the result.
Coming back down burns 60-70% of the climbing calorie cost and takes 50-70% of the climbing time. Eccentric quad load - the controlled lowering on every step - is what makes the descent so demanding on knees and legs. Plan rest stops on the way down, not just on the climb.
Common hiking calorie mistakes
Three errors push hiking calorie estimates off by 20-50%. First, using net elevation instead of cumulative gain - an undulating ridge with five 100 m climbs has 500 m of gain, not whatever the start-to-end difference is. Second, applying a flat-trail MET to terrain that is anything but. Third, forgetting that pace itself slows on steep ground, so the time blows out.
A practical check: if the calculator says a 12 km loop with 800 m gain should take 3.5 hours, and your trail apps usually predict 5 hours for similar profiles, your flat pace input is too fast. Dial it down 1 km/h and rerun.
Trail difficulty and hiking fitness
The U.S. Shenandoah National Park hike difficulty rating and several European systems use a single difficulty score combining distance and elevation: ASI = (cumulative gain in feet x 2 x miles) ^ 0.5. Anything under 50 is easy, 50-100 moderate, 100+ strenuous. The same loop with a 15 kg pack feels one full step harder. For training, log time and total elevation gain rather than distance - the climb is where fitness shows up.