Calories Burned Calculator
Estimate calories burned during exercise from body weight, activity intensity (METs), and duration. Use it to track exercise contribution to your daily calorie balance and to compare relative energy cost of different activities.
Last updated: May 2026
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About this calculator
The formula is: calories burned = weight × intensity × (duration / 60). The result is total calories expended during the activity. The intensity factor is the activity's MET (Metabolic Equivalent of Task) value — a standardized measure of energy expenditure where 1 MET equals resting metabolic rate (~1 kcal per kg of body weight per hour). Common MET values: sleep 0.9; sitting quietly 1.0; light walking 2.5-3.5; brisk walking 4-5; bicycling moderate 6-8; running 8 min/mile 12; running 6 min/mile 16; swimming moderate 7-8; weightlifting moderate 5-6; HIIT 8-12; rock climbing 8-11. The compendium of physical activities (Ainsworth et al., updated 2011) catalogs MET values for hundreds of activities. Multiplying by weight (kg) gives kcal/hour at that intensity; dividing duration by 60 converts minutes to hours. Edge cases: zero weight, intensity, or duration produces zero calories. The formula is a rough estimate — real calorie burn varies 10-30% between individuals at the same weight and activity due to differences in fitness level (trained athletes burn fewer calories at the same external intensity), body composition (more muscle = higher resting metabolism), age, sex, and metabolic efficiency. Heart-rate-based estimates from fitness trackers and smartwatches can be more accurate than MET-based formulas because they capture individual cardiovascular response, but even those have ~15-25% error vs. lab gold-standard indirect calorimetry. For weight management, treat any calorie-burn estimate as directional rather than precise; the bigger lever is consistent daily activity over weeks and months rather than counting exact calories per workout.
How to use
Example 1 — Moderate run. A 70 kg person runs at 8 mph (MET ~11.5) for 45 minutes. Enter 70 for Weight, 11.5 for Intensity, 45 for Duration. Result: 70 × 11.5 × (45/60) = 70 × 11.5 × 0.75 = 603.75 calories. ✓ A reasonable estimate for a 45-minute moderate run; real expenditure could range 540-680 depending on terrain, fitness level, and individual metabolic efficiency. Example 2 — Strength training session. An 85 kg person does moderate weightlifting (MET ~5) for 60 minutes. Enter 85, 5, 60. Result: 85 × 5 × (60/60) = 425 calories. ✓ Weightlifting burns fewer calories than continuous cardio because of rest periods between sets, but produces meaningful "afterburn" (EPOC — excess post-exercise oxygen consumption) that can add 6-15% more calorie burn in the 24 hours after the workout. The formula doesn't capture EPOC; track via observed weight trend over 4-6 weeks rather than session-by-session.
Frequently asked questions
What is a MET and how is it measured?
A MET (Metabolic Equivalent of Task) is a measure of how much energy an activity requires compared to resting metabolism. 1 MET equals the energy spent sitting quietly, approximately 1 kcal per kg of body weight per hour, or 3.5 mL of oxygen per kg per minute. Activities are categorized by MET value in the Compendium of Physical Activities (Ainsworth et al., 2011 update). Light activity: under 3 METs (walking slowly, light housework). Moderate: 3-6 METs (brisk walking, casual cycling, dancing). Vigorous: 6+ METs (running, fast cycling, HIIT). Public health guidelines (CDC, WHO) recommend 150 minutes of moderate or 75 minutes of vigorous activity per week. MET values are population averages; individual energy expenditure varies based on fitness level, body composition, and movement efficiency.
How accurate are calorie-burn estimates from fitness trackers?
Generally within 15-30% of true lab-measured expenditure. Trackers use heart rate plus algorithmic estimates that include user demographics, activity type detection, and movement intensity. The biggest errors come from: activities with significant resistance (weightlifting, where heart rate doesn't scale linearly with energy expenditure); steady-state cardio in trained athletes (heart rate is suppressed relative to work output); high-intensity intervals (rapid heart rate changes don't map cleanly to calorie burn). Wrist-based heart rate sensors are also less accurate than chest straps, particularly during high-movement activities. For weight management purposes, treat tracker calorie estimates as directional; the bigger lever is consistent activity patterns and dietary calorie awareness rather than precise tracker numbers. Indirect calorimetry (measuring oxygen consumption in a lab) is the gold standard but impractical outside research settings.
Does weight affect calories burned?
Yes, significantly. The MET-based formula multiplies by body weight because heavier people burn more calories doing the same activity — moving more mass requires more energy. A 70 kg person walking briskly (5 METs) for an hour burns 350 calories; a 100 kg person walking the same pace burns 500 calories. This is why per-mile or per-hour calorie burn varies by individual. For weight loss specifically, this creates a paradox: as you lose weight, you burn fewer calories at the same activity, so calorie deficit shrinks unless you increase intensity, duration, or further reduce intake. Many people experience "weight loss plateau" partly because of this metabolic adaptation. For body weight in pounds, convert to kg first (lbs ÷ 2.205 = kg) before plugging into MET-based formulas. Body composition also matters: muscle is more metabolically active than fat, so a 70 kg muscular person burns slightly more at rest than a 70 kg less-muscular person.
What are the most common mistakes people make with calorie-burn estimates?
The biggest is over-estimating workout calorie burn and "eating back" too much — leading to weight maintenance instead of loss. Tracker errors plus self-reported intake errors (which typically under-count by 20-40%) combine to make calorie counting unreliable for weight management. The second is fixating on session-level calorie burn when total daily activity (NEAT — non-exercise activity thermogenesis) matters more; a sedentary day with one workout can burn fewer calories than an active day without structured exercise. The third is comparing calorie burn across activities at the same duration; 30 minutes of running burns more than 30 minutes of yoga, but they serve different fitness purposes (cardio vs flexibility/strength). The fourth is using outdated MET values; the 2011 compendium revision changed several values from earlier versions. The fifth is treating tracker estimates as precise rather than directional. For weight management, focus on weekly trends and consistent habits over precise daily calculations.
When should I not use this calculator?
Skip it for precise nutritional planning where you need accuracy under 5%; lab-grade indirect calorimetry is the only method that delivers that precision. It is the wrong tool for very high-intensity intervals where MET values are imprecise; heart-rate-based monitoring during HIIT gives better individual estimates. Do not use it for clinical purposes (post-surgery rehabilitation, cardiac event recovery) where exercise intensity needs precise medical supervision. For weightlifting and resistance training, MET values understate true energy expenditure because they don't capture EPOC (excess post-exercise oxygen consumption, the "afterburn"); add 5-15% to the calculator output for resistance-heavy sessions. And for general weight management, the calculator output is useful as a directional check but not as a precise budget — combine with weekly weigh-ins and adjust intake based on observed weight trend rather than precise calorie math.