Calories Burned by Activity Calculator

What is MET?

MET (Metabolic Equivalent of Task) represents the energy cost of an activity relative to resting. 1 MET = sitting quietly. 3.5 METs = leisurely walking. 10 METs = vigorous running. Calories = MET × weight (kg) × time (hours).

What's the key thing to understand about Accuracy Limitations?

MET-based estimates assume average body composition and efficiency. Actual calorie burn varies by 15–20% between individuals of the same weight due to fitness level, muscle mass, and exercise economy. A fit runner burns fewer calories at 10 km/h than an unfit one — their body is more efficient.

What do I need to know about Exercise and Diet?

Exercise contributes 20–30% of most people's total energy expenditure. Diet changes are more controllable and consistent for weight management. However, exercise provides metabolic, cardiovascular, and mental health benefits far beyond its calorie contribution.

What's the key thing to understand about Progressive Overload and Recovery?

For sustained fitness improvements, progressive overload (gradually increasing training load over time) combined with adequate recovery is essential. The principle: the body adapts to a training stimulus, then requires a new stimulus to continue improving. Without progressive overload, fitness plateaus. Without adequate recovery, overtraining prevents adaptation and increases injury risk. Signs of overtraining: persistent fatigue, declining performance despite consistent training, increased resting heart rate, disturbed sleep, and mood changes such as irritability or loss of motivation. If these signs persist for more than a week or two, reduce training volume and intensity, prioritise sleep and nutrition, and consider a full rest week before resuming progressive overload.

What's the key thing to understand about MET Values?

Activity-based calorie calculators, including this one, generally work from MET values — Metabolic Equivalent of Task — a standardised way of expressing how intense an activity is relative to resting. One MET is defined as the energy cost of sitting quietly (roughly 3.5ml of oxygen consumed per kilogram of body weight per minute), and every activity is assigned a multiple of that baseline: walking at a brisk pace is roughly 3.5 METs, moderate cycling around 6-8 METs, running at a 10-minute-mile pace around 10 METs, and vigorous activities like competitive squash or fast swimming can exceed 10-12 METs. Because MET values scale with body weight, converting a MET value into actual calories burned uses the formula: calories/minute = MET × weight (kg) × 3.5 ÷ 200 — which is why two people doing the identical activity at the identical intensity burn different total calories, simply because a heavier body requires more energy to move. The MET system, compiled and regularly updated in the Compendium of Physical Activities (an academic reference used by exercise scientists worldwide), covers hundreds of specific activities and is the standard that underlies most calorie-burn calculators, fitness trackers, and exercise machine displays, even when the device itself doesn't disclose that's what it's using.

What should I know about Why Different Devices Disagree on Calorie Burn?

It's a common and frustrating experience to see three different numbers for the same workout — one from a smartwatch, one from a gym machine, one from an app — and this happens because each uses different inputs and assumptions. MET-based estimates (used by most calculators and many gym machines) rely on population-average energy costs for a given activity and intensity, and don't account for individual differences in fitness level, movement efficiency, or exact pace within a broad category like 'jogging'. Heart-rate-based estimates (used by many wearables) assume a fairly direct relationship between heart rate and calorie burn, but this relationship is affected by factors unrelated to effort — such as caffeine, stress, heat, dehydration and certain medications — all of which can raise heart rate without a proportional rise in actual calories burned, causing overestimation. More advanced wearables that combine heart rate with motion-sensor data and personal profile information (age, weight, height, sometimes VO2 max estimate) tend to be more individually accurate, but validation studies comparing consumer wearables against lab-measured oxygen consumption have still found errors commonly in the 10-30% range, and sometimes considerably higher for atypical movement patterns like weightlifting or cycling (where wrist-based heart rate tracking struggles). None of these methods is 'wrong' exactly — they're each a reasonable estimate built on different trade-offs — which is why consistency in which method you use to track trends over time matters more than chasing an exact number.

Why Shouldn't Calorie Estimates Drive Eating Decisions Alone?

Calorie-burn estimates from MET tables, wearables or online calculators all carry meaningful error margins — commonly 15-30% even from well-calibrated devices — because they're built from population averages rather than measuring your actual metabolism during that specific session. Using these numbers to directly justify eating back the calories "earned" from exercise is one of the most common ways people accidentally stall weight loss or gain more than expected, because a modest overestimate of burn, compounded with a modest overestimate of how many calories a post-workout snack contains, can erase the entire deficit a workout was meant to create. The more reliable approach is to treat exercise calorie estimates as rough guidance for programming — deciding how much activity to do — rather than as a precise currency to spend on food. Tracking bodyweight trend and how clothes fit over weeks, alongside a consistent, reasonable eating pattern, gives a far more accurate signal of whether your overall energy balance is on track than any single workout's calorie count. Exercise still matters enormously for health, fitness, and making a modest calorie deficit more sustainable by allowing a slightly higher food intake — but the calorie number it generates is best treated as an estimate with real uncertainty, not a precise ledger entry to be spent at the vending machine.

Worked Example: Estimating Burn Across a Mixed Workout

Calories burned from an activity are estimated as MET value × body weight in kilograms × duration in hours, where 1 MET represents the energy cost of sitting quietly. This formula is why the same workout burns meaningfully different calorie totals for people of different body weights, even performing identical movements for identical durations.

Worked example: a 75kg person doing 20 minutes of brisk walking (MET 3.5) burns approximately 3.5 × 75 × (20/60) = 87.5 kcal. Following that with 20 minutes of moderate cycling (MET 7.5) burns approximately 7.5 × 75 × (20/60) = 187.5 kcal, and finishing with 20 minutes of bodyweight circuit training (MET 6.0) burns approximately 6.0 × 75 × (20/60) = 150 kcal. Adding the three segments together gives roughly 425 kcal for the full 60-minute mixed session — a useful illustration of how MET-based estimates scale additively across a varied workout, even though, as noted above, any single MET-based figure still carries a meaningful margin of error.

Does Afterburn (EPOC) Add Meaningfully to the MET-Based Estimate?

Excess post-exercise oxygen consumption (EPOC), sometimes called "afterburn," refers to the elevated calorie burn that continues for a period after a workout ends, as the body restores oxygen stores, clears metabolic byproducts, and repairs tissue. Standard MET-based calorie estimates, including the worked example above, capture only the calories burned during the activity itself and do not include this after-the-fact contribution. For most moderate-intensity steady-state activities like walking or easy cycling, EPOC adds only a small, often negligible amount on top of the MET-based figure. For genuinely high-intensity interval training or heavy resistance training, EPOC can add a more meaningful amount — commonly cited research suggests roughly an extra 6-15% of the workout's own calorie burn over the following hours, though this varies considerably between studies and individuals, and is still a secondary factor compared to the activity's own MET-based burn.

MET-Based Estimates vs Heart-Rate-Based Estimates

Two common ways to estimate calorie burn give different numbers for the same workout, and it helps to know why. A MET-based estimate (what this calculator uses) multiplies a fixed metabolic cost per activity by body weight and duration — it's consistent and repeatable, but blind to fitness level. A heart-rate-based estimate (what a fitness watch typically shows) reacts to how hard your individual heart is working, so it can register a higher burn for someone less fit doing the 'same' activity, and a lower one for a well-trained athlete whose heart rate barely rises.

Neither is 'wrong' — they're measuring slightly different things, which is the main reason a treadmill display, a watch, and a MET table rarely agree on the same session.