How Calories Burned Are Estimated: METs Explained

What a MET is

MET stands for metabolic equivalent of task. One MET is the energy cost of resting quietly, defined as an oxygen use of about 3.5 millilitres per kilogram of body weight per minute. An activity rated at 8 METs costs roughly eight times as much energy as resting.

Exercise guidelines group activities by intensity using the same scale:

Published tables of MET values vary slightly by source and by the exact speed or effort described, so treat the examples as ballpark figures.

The calorie formula

Because 1 MET is about 3.5 mL of oxygen per kg per minute, that is 210 mL per kg per hour. The body releases roughly 5 kcal for each litre of oxygen it uses, which works out to about 1 kcal per kg per hour for every MET.

kcal burned ≈ MET × body weight (kg) × time (hours)To use pounds, divide by 2.2046 to get kilograms first.

Worked example: a 70 kg person runs for 30 minutes at 8 METs. That is 8 × 70 × 0.5 = 280 kcal. The same run for people of different body weights shows why weight matters:

A 4-MET brisk walk for a full hour at 70 kg also comes to 4 × 70 × 1 = 280 kcal. The walk burns the same total with half the intensity, but it takes twice as long.

Working in pounds: a 160 lb person is 160 ÷ 2.2046 ≈ 72.6 kg. A 45-minute walk at 4 METs is 4 × 72.6 × 0.75 ≈ 218 kcal.

The formula also explains a well-known running rule of thumb. At about 10 km/h, running is rated at roughly 10 METs, so a 70 kg runner uses about 10 × 70 × 1 = 700 kcal in an hour and covers 10 km in that time. That is close to 1 kcal per kilogram of body weight for each kilometre, or about 70 kcal per km. Treat it as a gross, back-of-the-envelope figure.

Gross versus net calories

The formula above gives gross calories: the total energy used during the activity, including the 1 MET your body would have burned anyway at rest. The net figure counts only the extra effort.

net kcal ≈ (MET − 1) × body weight (kg) × time (hours)

For the 70 kg runner, net burn is (8 − 1) × 70 × 0.5 = 245 kcal rather than 280. The distinction matters when you add exercise to a daily budget that already counts resting burn: using the gross number counts the resting part twice.

The difference grows with the length of the session. For a two-hour hike at 6 METs and 70 kg, the gross figure is 6 × 70 × 2 = 840 kcal, but the net figure is 5 × 70 × 2 = 700 kcal, a gap of 140. Whichever you choose, use the same one each time so your comparisons stay consistent.

Why it is only an estimate

• MET values are averages. They come from measurements on groups of people, so your own cost at a given pace can be higher or lower.
• Efficiency differs. Skilled, well-trained movers often use less energy for the same speed, and conditions such as hills, wind, heat or a soft surface change the cost.
• Weight is not the only factor. Body composition, age and sex also affect energy use, and the simple formula ignores them.
• Devices add their own error. Trackers combine MET-like models with heart rate and movement, and their calorie estimates can be well off for some activities.

Use the numbers for comparison and trends, such as which of two workouts costs more or how a typical week adds up, rather than as an exact ledger. If you are using exercise calories alongside a food plan, consider counting only part of the estimate and watching how your weight changes over several weeks.

For a daily budget that already includes activity, try the calorie calculator or the TDEE calculator.

This article is general education, not medical or dietary advice. For personal calorie targets or if you have a health condition, speak with a doctor or registered dietitian.