Calories Burned by Activity

Overview

A calories-burned-by-activity calculator turns a few minutes of exercise into an estimated energy expenditure using the MET (metabolic equivalent of task) system. MET values are tabulated for hundreds of activities — from sleeping to competitive cycling — and are designed to be comparable across body sizes by anchoring to resting metabolic rate.

This kind of estimate is most useful for planning a calorie deficit, comparing workout options, or sanity-checking what a fitness watch reports. Watches add heart-rate inference on top, but MET tables remain the underlying scientific backbone and are typically accurate within 10 to 20% for moderate intensities.

How it works

One MET equals roughly 3.5 ml of oxygen per kilogram per minute, which corresponds to about 1 kcal per kilogram per hour at rest. The classic calorie formula is kcal = MET × body_weight_kg × duration_hours. So a 70 kg adult walking for 30 minutes at a 3.5 MET pace burns 3.5 × 70 × 0.5 ≈ 122 kcal.

MET values come from the Compendium of Physical Activities, a widely cited reference used by exercise physiologists. Higher intensity efforts have higher MET values: light yoga is about 2.5, brisk walking 4.3, jogging 8, running at 10 km/h around 10, and vigorous cycling above 12. Body weight scales linearly because heavier bodies require more energy to move the same distance.

Examples

• A 70 kg adult walking briskly (MET 4.3) for 45 minutes: 4.3 × 70 × 0.75 ≈ 226 kcal.
• An 85 kg cyclist riding moderately (MET 7.5) for one hour: 7.5 × 85 × 1 ≈ 638 kcal.
• A 60 kg runner at 10 km/h (MET 10) for 30 minutes: 10 × 60 × 0.5 = 300 kcal.
• A 75 kg desk worker spending one hour stretching (MET 2.3): 2.3 × 75 × 1 ≈ 173 kcal — modest, but better than seated.

FAQ

Why does my watch say something different?
Watches blend MET with heart-rate and movement data, so they adjust for actual effort rather than the tabulated average. Both estimates are approximations.

Does MET account for resting metabolism?
Yes — one MET already represents your baseline burn, so the equation captures total energy use during the activity, not just the excess.

Are MET values accurate for very fit people?
Highly trained athletes often have a higher mechanical efficiency, so they may burn slightly fewer calories at the same MET. The reverse is also true for novices.

How should I use this with weight-loss goals?
Underestimate burn and overestimate intake when in doubt. A 10% buffer on each side prevents the common trap of "eating back" exercise calories.

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