What is a MET, and why does it decide your calorie burn?

Direct answer. MET stands for metabolic equivalent of task. It compares any activity to your resting burn. The Exercise Calorie Calculator uses one standard formula: calories = MET × weight (kg) × hours. The MET does the deciding because it sets the multiplier. Everything else — your weight, your time — just scales it. This guide explains where MET values come from, how accurate they are, and how to use them this week.

What is a MET, exactly?

MET means metabolic equivalent of task. It is a ratio. Scientists divide the energy an activity costs by the energy your body spends at rest. Sitting quietly equals 1 MET. Brisk walking equals 4.3 METs. That means brisk walking costs 4.3 times your resting burn.

Two standardized definitions carry the system. First, 1 MET ≈ 3.5 mL of oxygen per kilogram of body weight per minute. Second, 1 MET ≈ 1 kcal per kilogram per hour. The 2011 Compendium paper states it plainly: “We use the definition of a MET as described by Balke to be 3.5 mL·kg⁻¹·min⁻¹, often characterized as the metabolic cost of resting quietly” (Ainsworth et al., 2011).

“One MET is defined as 1 kcal/kg/hour and is roughly equivalent to the energy cost of sitting quietly.”

— Compendium of Physical Activities, maintained by Barbara E. Ainsworth, PhD, College of Health Solutions, Arizona State University (pacompendium.com, 2024)

Why does one number decide so much? Because it is universal. METs strip out body weight, age and sex from the intensity label. Two people can compare a workout fairly, even when their calorie totals differ. Research shows this is why METs anchor national activity guidelines, clinical exercise tests and every calorie app on your phone.

How does a MET become calories burned?

Three inputs. The MET from the activity. Your weight in kilograms. Your time in hours. Multiply them. That is the whole calculation.

calories = MET × weight (kg) × duration (hours)

Worked example. Running at a moderate pace (MET 9.8) for 30 minutes at 70 kg: 9.8 × 70 × 0.5 = 343 kcal. Now swap the activity. Brisk walking (MET 4.3) for the same 30 minutes at 70 kg: 4.3 × 70 × 0.5 = 150.5 kcal. Same body, same time — the MET did all the deciding. The gap between those two numbers is 192.5 kcal in half an hour.

Weight acts as a straight multiplier. A 90 kg runner burns 9.8 × 90 × 0.5 = 441 kcal for that session. A 50 kg runner burns 9.8 × 50 × 0.5 = 245 kcal. Same pace, same effort label, 80% more calories for the heavier runner. Data from the Compendium shows doubling weight roughly doubles the burn — the MET itself never changes.

What does each MET level look like in real life?

MET values turn abstract effort into a ladder. Below is the practical range, from sleep to sprint. Colors mark the standard intensity bands: sedentary and light in pale, moderate in mint, vigorous in black.

The same ladder, with calorie totals for a 70 kg person over 30 minutes:

Source: activity values from our dataset, derived from the Compendium. Browse all 125+ entries in the activity directory.

Where do MET values come from?

One source dominates: the Compendium of Physical Activities. Researchers started it in 1989 and published it in 1993. It has been updated three times since. Each update screens new lab studies and replaces guesses with measurements.

1. 1993 — first edition: 477 activities across 19 categories.
2. 2000 — grows to 605 activities and 21 categories.
3. 2011 — reaches 821 activities; 561 (68%) carry measured MET values.
4. 2024 — hits 1,114 activities in 22 categories; 912 (82%) are lab-measured.

That 2024 refresh was heavy work. The team screened 32,173 abstracts, read 1,507 full papers, and extracted 2,356 energy values from 701 studies. They added 303 new activities, changed 176 existing MET values, and created a whole new category for video games. Since 1993, the catalogue has grown by 134% — more than doubling the world’s shared vocabulary for movement.

The method behind the numbers is indirect calorimetry: subjects breathe into a machine that measures oxygen use. Measured values are labeled. Estimated values are labeled too — only 18.5% of the 2024 list remains estimated. Industry analysis shows every other calorie tool on the market traces back to this one dataset, in whole or in part.

How do METs define light, moderate and vigorous?

Public health agencies use MET cut-points to draw intensity zones. The Compendium sets the official bands. You can read any activity label straight off the number.

Why these lines? Research shows they separate health outcomes. The 2018 U.S. Physical Activity Guidelines and the WHO 2020 guidelines both recommend150–300 minutes of moderate activity per week, or 75–150 minutes of vigorous activity. In MET terms, that volume equals roughly 500–1,000 MET-minutes per week — enough to reduce morbidity and mortality risk, according to the 2024 Compendium’s analysis of the guidelines.

MET-minutes make targets easy to score. Multiply the MET by your minutes. A 30-minute brisk walk scores 4.3 × 30 = 129 MET-minutes. Five of those walks a week score 645. You just cleared the minimum guideline with one habit.

Why does one MET burn different calories for different people?

A MET labels intensity, not your personal burn. Three factors stretch the final number: body weight, body composition, and your individual resting metabolism.

Body weight scales everything. The same session, four body weights:

Weight multiplies the burn; the MET never moves. Heavier people always burn more for the same work — that is physics, not fitness.

Body composition hides inside the weight. Muscle is more metabolically active than fat. Two people at 80 kg can burn differently at rest and during strength work. The Compendium authors are direct about the limit: “the Compendium can serve as a starting point for prescribing individual activities but does not reflect precise individual EE values” (Herrmann, Willis, Ainsworth et al., 2024). Their paper notes women with obesity burned roughly 8–15% more across treadmill speeds than women without obesity in one comparison study.

Resting metabolism varies too. The fixed 1-MET baseline assumes 3.5 mL/kg/min for everyone. Measured resting oxygen use often runs lower. In the E-MECHANIC trial, sedentary adults’ measured rest came in 30.4% belowthe standard estimate — a gap of 699 kcal per day. That is why researchers built “corrected METs” that adjust for age, sex, height and weight, and why the Older Adult Compendium uses a different baseline entirely.

How accurate is a MET-based estimate?

The formula itself is arithmetic — it cannot be wrong. Accuracy lives in the inputs. One large trial shows exactly where estimates drift. Researchers call it the honest map of MET error.

The E-MECHANIC case study, in numbers

• Setup: 103 sedentary adults with overweight or obesity trained on treadmills for 24 weeks.
• Method: scientists compared equation estimates against indirect calorimetry, the gold standard.
• Easy walking: the equation missed by just 0.44% — essentially perfect.
• Hard efforts: error climbed to 9.2% at training intensity and 20.3% at max effort.
• After training: estimates got worse, not better — easy-walk error rose to 5.1% as participants became more efficient.
• Real-world impact: for Black women in the trial, the gap hit 29 kcal per hour of walking — 209 kcal per week at guideline volume, or 3.1 lb less fat loss per year than predicted.

“These findings support future efforts to improve the accuracy of metabolic equations, especially in diverse populations.”

— Rachel Matthews, PhD, School of Kinesiology, Louisiana State University, lead author of the E-MECHANIC secondary analysis (Medicine & Science in Sports & Exercise, 2025)

The pattern is consistent. Estimates stay tight at light and moderate effort. They drift upward as intensity rises. Expect roughly ±10% on everyday workouts, and treat hard-intensity numbers as upper bounds. Also remember the original ACSM equations were built from just five young trained men. Small samples make narrow promises.

METs vs. smartwatches vs. heart rate: which should you trust?

Three popular methods compete for your attention. Each measures something different. The table below shows what studies reported between 2024 and 2025.

“For MAPE, all subgroups for EE exceeded the 10% validity threshold, while none of the subgroups for HR exceeded this threshold.”

— Ju-Pil Choe and Minsoo Kang, professor of sport analytics, Health and Sport Analytics Laboratory, University of Mississippi (meta-analysis of 56 studies, 270 effect sizes, Physiological Measurement, 2025)

The practical read: your watch is trustworthy for heart rate, weaker for calories. MET math is trustworthy for comparisons, weaker for your personal physiology. Use both, anchor on trends. Industry analysis shows the winning setup is simple — let the MET table plan the work, let the watch confirm you did it.

Case study: what 30 minutes of MET math does per year

Numbers get persuasive when they compound. Consider one realistic swap: replace 30 minutes of evening TV with 30 minutes of brisk walking, every day.

Now the honest footnote. E-MECHANIC documented “weight compensators” — people whose real weight loss fell short of the equation’s prediction. Bodies adapt, appetites answer back, and daily life wobbles. Treat the 11 lb figure as the ceiling, not the promise. The direction of the effect is solid; the exact outcome depends on your diet, sleep and consistency.

How do you use METs to plan your week?

METs turn vague goals into countable targets. Follow the five steps below, then score the week in one number.

1. Find your activity’s MET. Search the freeCompendium database, or open our activity directory. Brisk walking is 4.3; moderate running is 9.8.
2. Convert your weight to kilograms. Divide pounds by 2.2. A 154 lb person weighs about 70 kg.
3. Multiply MET × weight (kg) × hours. That product is your calorie burn for the session.
4. Score your week in MET-minutes. Multiply each session’s MET by its minutes. Total the week. Target 500–1,000 MET-minutes.
5. Review every Sunday. Compare weekly totals, not daily noise. Extend duration before raising intensity when you fall short.

One brisk-walking habit clears the WHO and U.S. guideline minimum. Data from the 2024 Compendium’s guideline analysis (500–1,000 MET-min/week).

What is changing in MET science for 2026?

MET science is not finished. Four shifts are already visible.

• The Compendium now splits by population. Separate editions cover youth (ages 6–18), adults 19–59, adults 60+, and wheelchair users — each with a different resting baseline. Expect more niche editions as measurement improves.
• Wearables are learning METs directly. A June 2025 study in Scientific Reports trained machine-learning models on smartwatch accelerometers and gyroscopes to estimate minute-by-minute METs — with BMI built into the algorithm, targeting a known source of bias.
• Guidelines may go device-first. The 2024 Compendium authors argue that combining questionnaires with device data could eventually produce new device-based physical activity guidelines.
• Estimated values keep shrinking. Estimates fell to 18.5% of the adult list in 2024, down from 32% in 2011. Each refresh replaces assumptions with lab data.

Your 7-day action plan

Ten minutes today. Two minutes a week after. Here is the sequence.

1. Day 1 (10 min): baseline. Log your daily screen time and steps.
2. Day 2 (5 min): look up METs for the five activities you do most.
3. Day 3 (5 min): run the numbers in the mini calculator above.
4. Day 4: schedule three 30-minute brisk walks for the week.
5. Day 5: cross 600 MET-minutes — your first guideline clear.
6. Day 6: swap one sedentary block for a 3–4 MET activity.
7. Day 7 (5 min): total the week. Aim for 500–1,000 MET-minutes.

Keep going with two habits. Total your MET-minutes every Sunday. Open thecalories burned calculator whenever a new activity enters your routine. For the other half of the equation — how much you eat — run your numbers through the daily calorie calculator for BMR and TDEE.

Sources and further reading

1. Herrmann SD, Willis EA, Ainsworth BE, et al. “2024 Adult Compendium of Physical Activities: A third update of the energy costs of human activities.”Journal of Sport and Health Science. 2024;13(1):6–12.Read the open-access study.
2. Ainsworth BE, Haskell WL, Herrmann SD, et al. “2011 Compendium of Physical Activities: a second update of codes and MET values.”Medicine & Science in Sports & Exercise. 2011;43(8):1575–1581.View the abstract on PubMed.
3. Matthews R, Höchsmann C, Erickson ML, et al. “Modulators of Energy Expenditure Accuracy in Adults with Overweight or Obesity: E-MECHANIC Secondary Analyses.”Medicine & Science in Sports & Exercise. 2025;57(3):470–480.Read the open-access study.
4. Choe J-P, Kang M. “Apple watch accuracy in monitoring health metrics: a systematic review and meta-analysis.” Physiological Measurement. 2025;46(4):04TR01.Open the DOI.
5. Lyng Danielsson M, Vergeer M, Plasqui G, Baumgart JK. “Accuracy of the Apple Watch Series 4 and Fitbit Versa for Assessing Energy Expenditure and Heart Rate of Wheelchair Users.” JMIR Formative Research. 2024;8:e52312.View the abstract on PubMed.
6. Compendium of Physical Activities. “Definition of terms used in the adult compendium.” Maintained at pacompendium.com.Visit the official database.
7. World Health Organization. “Physical activity” fact sheet (2020 guidelines).Read the WHO guideline summary.
8. Willis EA, Herrmann SD, Barreira TV, et al. “Older Adult Compendium of Physical Activities.” Journal of Sport and Health Science. 2024;13:13–17.Open the DOI.

Related guides on this site

• How the calories burned calculator works — the full formula, plus what it does not model.
• Activity directory — 125+ activities with MET values and calorie charts.
• Daily calorie calculator — BMR, TDEE and weight-loss targets.
• Frequently asked questions — quick answers on methods, units and accuracy.
• Brisk walking calories — MET 4.3, chart and calculator.
• Running calories — MET 9.8, chart and calculator.

Medical disclaimer

This guide provides general educational estimates only. It is not medical advice, diagnosis or treatment. Do not begin, stop or change an exercise program based on these numbers alone. If you have a chronic condition — especially cardiovascular disease, diabetes, hypertension or joint problems — or are pregnant, postpartum, or returning from injury, consult a qualified healthcare professional first. If exercise causes chest pain, faintness or severe shortness of breath, stop immediately and seek medical help.