Calories Burned Calculator

What a MET actually is

A MET (Metabolic Equivalent of Task) is the energy cost of an activity relative to resting. One MET = 3.5 mL O₂ per kg of body weight per minute = approximately 1 kcal per kg of body weight per hour. So a 70 kg person at rest burns about 70 kcal/hour. The same person walking briskly at MET 5 burns 5 × 70 = 350 kcal/hour. The MET system was standardised by the Ainsworth Compendium of Physical Activities, first published in 1993 and updated in 2000 and 2011 (Ainsworth et al., Medicine & Science in Sports & Exercise). The 2011 edition lists MET values for over 800 activities and is the canonical reference for physical activity researchers and clinicians.

Why your wearable disagrees with this calculator

Apple Watch, Garmin, Fitbit, and Whoop don't use MET tables. They use heart rate, accelerometer data, your weight, and proprietary algorithms — and they're noisy. The 2017 Shcherbina et al. Stanford study compared seven wrist-worn devices to indirect calorimetry and found heart-rate readings were generally accurate (median error 5%) but calorie estimates ranged from 27% to 93% mean absolute error across devices. Apple Watch had the lowest error at 27%, Samsung Gear S2 the highest at 93%. None were better than ±20%. The MET-based estimate here is no more or less accurate than a wearable for any individual — it's a different kind of estimate with different sources of error.

The exercise calorie compensation trap

Tracking exercise calories and then "earning" food rewards is one of the most reliably ineffective weight-loss strategies. Three reasons. First, calorie estimates are noisy (±20–40%), so the calculation is wrong from the start. Second, compensatory behaviour — eating slightly more, moving less the rest of the day — typically erases 50–75% of exercise calorie expenditure within a few days. Third, perceived effort drives much larger food compensation than actual energy expenditure: 30 minutes of running feels like it should "earn" a 500 kcal meal, but the actual deficit was maybe 250 kcal net of compensation. Track total daily intake against your TDEE; treat exercise calories as a bonus, not a budget to spend.

EPOC — the "afterburn" effect

Excess Post-Exercise Oxygen Consumption is the elevated metabolic rate following a hard workout while the body restores oxygen debt, replenishes muscle glycogen, and clears lactate. For moderate-intensity steady-state cardio, EPOC adds roughly 6–15% on top of the workout calorie cost over 1–3 hours. For HIIT and heavy resistance training, EPOC can reach 15–20% over 12–48 hours. The popular claim that HIIT "boosts metabolism for 24+ hours and burns hundreds of extra calories" is overstated by 2–5× in most popular sources. Average EPOC for a 30-minute HIIT session is ~50–100 additional calories over the day — meaningful but not metabolism-altering.

Related tools

• TDEE Calculator — your daily maintenance
• Calorie Deficit Calculator
• Heart Rate Zones Calculator
• Maintenance Calorie Calculator

Frequently asked questions

How accurate are MET-based calorie estimates?

For moderate-intensity steady-state activities (walking, cycling, swimming), MET estimates are reasonably accurate — within 10–20% of indirect calorimetry for the population average. For high-intensity intervals, sprinting, very heavy resistance training, and activities heavily dependent on skill and efficiency (rowing technique, swimming stroke), MET values are population averages that may over- or under-estimate by 20–30% for any individual. Wearable devices using heart-rate and motion (Apple Watch, Garmin) are similarly noisy — the 2017 Stanford study by Shcherbina et al. found heart-rate-based calorie estimates had error of ±27–93% across six popular devices.

Why does my Apple Watch say I burned different calories than this calculator?

Wearables use heart rate, motion data, your weight, and proprietary algorithms — not MET tables. They tend to overestimate by 10–40% for most activities because they include resting metabolism in the count (gross calories) and because algorithms are tuned for engagement, not accuracy. The Stanford 2017 study found Apple Watch had the lowest error of six tested devices but still ~27% mean absolute error for calorie estimation. For tracking trends day-to-day on the same device, wearables are useful; for absolute calorie counts, treat them as ±25%.

Should I eat back the calories I burn during exercise?

Partly. Most people overestimate exercise calories by 30–50% and then over-eat back. Hall and colleagues at NIH have demonstrated that "compensation" — eating more after exercise, moving less the rest of the day — typically erases 50–75% of exercise calorie burn over a week. If you're cutting and using a TDEE × activity multiplier (sedentary to very active), the multiplier already includes typical exercise — don't double-count by also eating back tracker calories. If you're tracking only BMR and adding exercise calories separately, eat back 50–70% of the tracker estimate.

Does muscle mass affect calories burned?

Indirectly. Lean body mass (muscle) is the dominant determinant of resting metabolic rate — every kg of LBM costs ~13 kcal/day at rest. During activity, calorie burn scales with total body mass, not specifically LBM, so a 100 kg muscular person and a 100 kg less-muscular person burn similar calories at the same activity. The bigger effect of muscle is on the baseline — more muscle means more BMR means more total daily calories burned even without changing activity.

What about EPOC ("afterburn")?

Excess Post-Exercise Oxygen Consumption is real but small. For moderate steady-state exercise, EPOC adds 6–15% on top of the workout calorie cost. For high-intensity interval training and heavy resistance training, EPOC can be 10–20%. The much-promoted "metabolic boost lasting 24+ hours" from HIIT has been measured experimentally and the additional 24-hour calorie burn averages 80–200 kcal — meaningful but not enough to justify the popular claims. The Ainsworth Compendium MET values already incorporate average post-activity metabolic cost.