Estimate calories burned during any exercise based on activity, duration, and your body weight.
Calories Burned
Calories = MET × body weight (kg) × time (hours)
MET = Metabolic Equivalent of Task
1.0 = sitting quietly
3.5 = walking 3.5 mph
8.0 = running 6 mph
Body weight in kg = lbs ÷ 2.205
MET values come from the Compendium of Physical Activities (Arizona State University). Estimates are accurate within ±20-30% — individual fitness, efficiency, and intensity affect actual burn.
MET (Metabolic Equivalent of Task) measures how much energy an activity requires relative to sitting at rest (MET = 1.0). Running at 6 mph has a MET of approximately 8 — it burns about 8 times the energy of sitting. Multiplying MET by body weight in kilograms and time in hours gives calories burned.
Body weight is a direct input because heavier people burn more calories doing the same activity — there is simply more mass to move. A 200-pound person running at 6 mph burns roughly 38% more calories than a 145-pound person at the same pace and duration.
MET values are population averages based on measured oxygen consumption in studies. Individual results vary based on fitness level (fit runners are more efficient and burn slightly fewer calories per mile), terrain, temperature, and exact pace. Treat these estimates as useful approximations, not precise measurements.
Exercise and Weight Loss: Setting Realistic Expectations
Exercise contributes to weight loss, but its direct caloric contribution is often smaller than people expect. A 45-minute run at 6 mph burns approximately 400-600 calories for an average adult — an amount that can be offset by a single restaurant meal. This is not an argument against exercise; it is context for why dietary changes are typically the primary driver of weight loss while exercise plays a supporting role.
Where exercise excels for weight management: it preserves muscle mass during caloric restriction (crucial for avoiding the "skinny fat" outcome), partially counteracts metabolic adaptation, improves insulin sensitivity, and has well-documented mental health benefits that support adherence to any diet. A comprehensive approach combines moderate caloric restriction with regular exercise for better long-term outcomes than either alone.
Frequently Asked Questions
Wearables use heart rate data in addition to movement, which improves accuracy somewhat. However, studies consistently show most wearables overestimate calorie burn by 15-30% depending on activity type. Wrist-based heart rate monitoring is particularly inaccurate during high-intensity intervals and strength training. Use tracker data for relative comparison and trends rather than precise caloric accounting.
High-intensity activities burn the most per minute: running at high speed, rowing, jump rope, and HIIT circuits typically burn 10-15+ calories per minute for average-sized adults. However, lower-intensity activities accumulated over long periods — walking throughout the day — often exceed structured exercise for total daily calorie burn in sedentary individuals. This is called NEAT (Non-Exercise Activity Thermogenesis).
During the session, no — strength training typically burns 4-6 calories per minute versus 8-12 for moderate cardio. However, strength training elevates metabolism for 24-48 hours post-workout (EPOC — Excess Post-exercise Oxygen Consumption) and builds muscle that increases resting metabolic rate. Over weeks and months, a strength training program can meaningfully increase total daily calorie burn even on rest days.
FDA regulations allow up to 20% error in food label calorie counts, and restaurant calorie counts are even less reliable. Studies show restaurant items often contain 10-20% more calories than listed. This is why precise calorie tracking is inherently approximate — small errors compound across a day. Focus on consistent habits and weekly weight trends rather than perfect daily calorie accounting.