Rucking calorie calculator: how many calories does rucking burn?

Written by James Frost, founder of Flaming Phoenix and the maker of Phoenix Bars. Updated November 2026.

Quick answer: An 80 kg person carrying a 15 kg pack at a steady 5 km/h burns about 400 calories an hour on flat tarmac, about 670 on hilly ground and about 700 on soft sand. Rucking, or yomping in Royal Marines slang, burns more than walking, but how much more depends on your pack weight, pace, gradient and the surface under your boots. This calculator works in kilograms and km/h first, because you shouldn't need to convert your own bodyweight to use an American tool.

How this calculator works

The engine is the Pandolf load-carriage equation, developed at the US Army Research Institute of Environmental Medicine and still the most widely cited model for the energy cost of walking under load. It takes your body mass, pack mass, speed, gradient and a terrain factor: pavement or a treadmill counts as 1.0, a dirt trail 1.1, grass or light brush 1.2, rough ground 1.5, and soft sand 2.1, meaning sand more than doubles the cost of moving the same load. Because field validation studies have shown the original laboratory equation underestimates real-world cost, particularly at heavier loads, this calculator applies a 15% field correction and says so, which is more than most rucking calculators will tell you about their numbers.

The equation gives power in watts: 1.5W + 2.0(W + L)(L/W)² + η(W + L)(1.5V² + 0.35VG), where W is your weight in kg, L the load in kg, V speed in metres per second, G the gradient in % and η the terrain factor. Each watt is 0.86 calories an hour, and the calculator then adds its 15%. Worked example for an 80 kg person with a 15 kg pack at 5 km/h (1.39 m/s) on tarmac: 120 + 6.7 + 274.9 = about 402 watts, × 0.86 = 345 calories an hour, + 15% = about 400.

What actually drives the burn

What most rucking marketing skips: at an easy pace on tarmac, the pack itself adds less than you'd think. A 15 kg pack at 5 km/h adds about 15% over unloaded walking for an 80 kg person, roughly 50 calories an hour. What multiplies the burn is everything else. Push the same ruck onto a 6% gradient and the hourly cost climbs to about 670 kcal. Move it onto soft sand and you're near 700. Lift the pace to a 6.4 km/h military standard and it rises to about 570 on the flat. Pack weight matters, but speed, hills and surface are the real levers, which is what the equation predicts and what anyone who has yomped across Dartmoor already knows in their legs.

How many calories does rucking burn per hour?

For an 80 kg person with a 15 kg pack, expect about 400 calories an hour on flat tarmac at 5 km/h, about 520 at a brisk 6 km/h, about 530 on rolling ground, about 670 on hilly ground and about 700 on soft sand. A 19 km (12 mile) ruck at military pace, three hours at 6.4 km/h with that load, costs about 1,700 kcal on flat tarmac and more on trails or hills, the equivalent of two or three extra meals on top of a normal day.

The tables use the same equation as the calculator, including its 15% field correction. Figures are approximate calories per hour, rounded to the nearest 10. First, an 80 kg person on flat tarmac by pack weight and pace:

With a 15 kg pack at 5 km/h, by body weight and ground:

Rucking on a treadmill

Set the terrain to pavement and enter your treadmill incline as the gradient. A 1% incline is often suggested to mimic outdoor conditions, but that advice comes from running; at walking pace air resistance is tiny, so a flat treadmill is close to flat tarmac. Anything above 5% with a loaded pack turns a walk into serious work.

Fuelling a ruck

Rucking has a built-in irony: the activity is about carrying weight, and the fuel to sustain it adds more weight. That makes calories per gram the number that matters in your pack. Nuts, nut butter, cheese and flapjack all carry far more calories per gram than fruit or sandwiches. I make Phoenix Bars, high-calorie bars with up to 557 calories in a compact, 120g bar, about 4.6 calories per gram, and a Phoenix Bar is one way to keep the food side of the load light. For longer days under a bergen, see our guides to military field nutrition and the lightest high-calorie foods for backpacking, our pick of the best energy bars for hiking, and the highest calorie bars in the UK ranked by calories per gram.

Frequently asked questions

How many more calories does rucking burn than walking? At easy pace on flat tarmac, a moderate pack adds around 15 to 20%. Add hills, pace and rough ground and loaded marching can approach double an easy unloaded walk, though claims of triple the burn generally assume heavy loads, fast paces and steep terrain all at once.

How many calories does rucking with 30 lb burn? A 30 lb pack is about 13.6 kg. For an 80 kg person at 5 km/h on the flat, that's roughly 390 to 400 kcal per hour, and meaningfully more on gradients.

How many calories does a 12 mile ruck burn? Around 19 km at military pace takes about three hours, and with a 15 kg load costs an 80 kg carrier about 1,700 kcal on flat tarmac, and more on trails or hills.

Can I use this for weighted vest walking? Yes. Enter the vest weight as the pack weight; the equation models carried load the same way, and a vest's central position, if anything, carries slightly more efficiently than a high pack.

How many calories does rucking burn per mile? An 80 kg person with a 15 kg pack burns about 80 calories per km (130 per mile) at 5 km/h on the flat, and about 90 per km (145 per mile) at 6.4 km/h. Hills and soft ground push both figures up.

Does rucking burn more calories than running? Per hour, no: an 80 kg runner at 10 km/h burns roughly 800 calories an hour, about double a steady 5 km/h ruck with 15 kg. Per km they're close, at about 80 each, because running costs roughly 1 calorie per kg of body weight per km.

Hiking without a load? See calories burned hiking. Working out other sports, try our cycling calorie calculator, ultra running calorie calculator and swimming calorie calculator.

Written by James Frost, founder of Flaming Phoenix and the maker of Phoenix Bars. Calculator methodology based on the Pandolf load-carriage equation with a stated 15% field correction. Updated November 2026.

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Sources: Pandolf, Givoni and Goldman, the Pandolf load-carriage equation, Journal of Applied Physiology (1977); Phoenix Bar values from our own pack labels.