On average, rucking burns 400–600 calories per hour — roughly 2 to 3 times more than unweighted walking at the same pace. A 180 lb person rucking with a 35 lb pack at 3.5 mph on pavement burns approximately 500–550 kcal/hour. Exact figures scale with body weight, pack weight, speed, grade, and terrain, which is what the enhanced Pandolf equation computes.

RuckCalc uses the enhanced Pandolf equation with a load-ratio correction factor that addresses the documented 12–33% underestimation in the original 1977 formula (Drain et al., 2017). Individual results vary with fitness, body composition, and environmental conditions, but our outputs are typically within ±10–15% of laboratory-measured values — significantly more accurate than generic fitness trackers, which often err by ±30–50%.

The Pandolf equation is a U.S. Army Research Institute of Environmental Medicine (USARIEM) formula published by Pandolf, Givoni, and Goldman in 1977. It predicts the metabolic cost of load carriage as a function of body mass, load mass, walking velocity, terrain coefficient, and grade. It remains the most widely cited load-carriage model in exercise science and military operational research. Our implementation adds a modern correction factor for heavy loads and fast paces.

Start with 10% of your body weight, capped at 20 lbs. For most adults that means 15–20 lbs for the first 4–6 weeks, then increase by 5 lbs every 2–3 weeks as conditioning improves. The two most common rucking injuries — shin splints and lower-back strain — are almost always caused by starting too heavy, not by the activity itself.

For most adults, yes. Rucking burns roughly 75–80% of the calories that running burns at the same pace, with only a fraction of the joint impact. Because rucking is sustainable on a daily basis and running often is not, the long-run calorie deficit usually favors rucking. Our weight-loss tab projects how long it will take to hit your goal based on your specific ruck workout pattern.

A 15–20 minute mile pace (3.0–4.0 mph) is the rucking sweet spot — fast enough to elevate heart rate meaningfully, slow enough to preserve good posture under load. The GoRuck standard for event qualification is a 15-minute mile with a loaded pack. Our calculator handles any pace from 2.0 to 5.0 mph.

No. Any sturdy backpack plus household weight (water bottles, books, a dumbbell wrapped in a towel) is enough for your first month. Dedicated rucksacks with proper waist and chest straps become worthwhile once you're carrying 30+ lbs regularly — see our Gear Guide for specific pack recommendations by budget.

Dramatically. Soft sand carries a Pandolf terrain coefficient of 2.1, meaning it burns roughly 2.1× more calories than treadmill walking at the same speed. Pavement is 1.0, dirt road is 1.1, light brush is 1.2, swamp is 1.8. Grade matters too — each 1% uphill grade adds roughly 10% to calorie burn. Our calculator lets you pick from 8 terrain types and any grade from -20% to +20%.