How Calories Burned Are Estimated: the MET Method

"I ran for half an hour — how much did I burn?" The answer exercise science gives is disarmingly simple: every activity has an intensity rating, and calories are that rating times your weight times the time spent. That rating is called a MET, and once you understand it, every calorie-burn estimate you have ever seen starts making sense.

What a MET measures

MET stands for metabolic equivalent of task. One MET is the rate your body burns energy at complete rest — sitting still, breathing, keeping the lights on. Every other activity is expressed as a multiple of that baseline: walking at an average pace costs about 3.5 METs, meaning three and a half times your resting burn; cycling at a moderate effort is about 7.5; running pushes near 9.8. The scale runs from sleep (0.95) to all-out sprint efforts north of 20, and the values used in calculators come from the Compendium of Physical Activities, a standardized catalogue of measured intensities.

The formula: kcal = MET × weight × hours

The standard conversion multiplies intensity by body size by duration:

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

Worked example: an 80 kg person cycles at a moderate effort (7.5 METs) for 45 minutes. Calories = 7.5 × 80 × 0.75 = 450 kcal. The same person running for half an hour (9.8 METs) burns 9.8 × 80 × 0.5 ≈ 392 kcal — less than the ride, despite the higher intensity, because the session was shorter. Duration trades directly against intensity, which is why comparing activities only makes sense per hour or per session length.

Body weight enters linearly, so the same run costs a 55 kg runner about 270 kcal and a 95 kg runner about 465. The calculator's per-hour readout makes the scaling easy to see: for our 80 kg example, walking burns 280 kcal/hour (3.5 METs), cycling 600, running 784, and jumping rope — the standout at 12 METs — 953.

Why your tracker disagrees

If you wear a fitness tracker, expect its numbers to differ from the MET math — usually by tens of percent, occasionally more. Trackers blend heart rate, step counts, and your measured stride into a personalized model, and they credit movement the MET table knows nothing about: hills, headwinds, stop-and-go efforts, carrying a child up stairs. The MET approach is deliberately standardized — one value per activity, scaled only by weight — which makes it transparent and comparable but blind to your terrain and your fitness. A trained runner is more efficient than the table assumes; a beginner is less. Both effects are real and neither is in the formula.

Fitting the burn into your day

A hard 45-minute ride earning 450 kcal feels significant until you compare it with the full day's budget — a typical adult burns 2,000–3,000 kcal in total, mostly from the basal and everyday activity the workout sits on top of. That is the honest context for exercise in weight management: it is a valuable but modest lever, and the food side of the ledger is far easier to overshoot (the ride's earnings fit back in with one pastry). For how the whole daily balance works, see How a Calorie Deficit Works; and if you measure your sessions in distance rather than time, the pace math in How Running Pace Works pairs naturally with the MET math here.

Try it yourself

The Calories Burned Calculator applies the MET formula across 16 activities, in metric or imperial — pick the activity, enter weight and duration, and get the session total plus the per-hour rate. To convert step counts into calories through the same logic, the Steps to Calories Calculator walks the full pipeline from stride to energy. The Pace Calculator handles the time-distance-speed side, and the TDEE Calculator shows where your workouts sit inside total daily burn.