Almost every calorie-burn figure you have ever seen traces back to the same source: the Compendium of Physical Activities, a published table of MET values. One MET is your metabolic rate sitting quietly — defined as 3.5 ml of oxygen per kilogram per minute — and an activity rated at 8 METs costs eight times that. The conversion is:
Calories per minute = MET × 3.5 × body weight in kg ÷ 200
A 70 kg person runs for 30 minutes at 8 km/h, which the compendium rates at 8.3 METs.
Per minute: 8.3 × 3.5 × 70 ÷ 200 = 10.2 calories. Over 30 minutes that is 305 calories.
But there is a subtlety worth knowing. That 305 is the gross figure — it includes the calories you would have burned anyway just being alive for half an hour. Subtracting that baseline gives the net cost of the run:
(8.3 − 1) × 3.5 × 70 ÷ 200 = 8.9 per minute, or 268 calories net.
The 37-calorie difference is small on one run and large over a year. It also explains a common frustration: if you eat back the gross figure from your watch, you are double-counting your resting metabolism and quietly erasing part of your deficit.
| Activity | METs | 30 min at 70 kg |
|---|---|---|
| Walking, slow, 3.2 km/h | 2.8 | 103 cal |
| Walking, brisk, 5.6 km/h | 4.3 | 158 cal |
| Cycling, 16 to 19 km/h | 6.8 | 250 cal |
| Swimming laps, moderate | 5.8 | 213 cal |
| Weight training, vigorous | 6.0 | 221 cal |
| Running, 8 km/h | 8.3 | 305 cal |
| Running, 11.3 km/h | 11.0 | 404 cal |
| Hatha yoga | 2.5 | 92 cal |
| Football, casual | 7.0 | 257 cal |
Notice that burn scales linearly with body weight in this model. A 90 kg person running the same 30 minutes burns about 392 calories rather than 305 — moving more mass costs more energy, which is also why the same workout burns less as you lose weight.
This is the part fitness apps rarely admit. MET values are averages drawn from small laboratory samples, and individual oxygen cost for the same activity varies substantially:
Treat any single figure as plus or minus 20 to 30%. What the number is genuinely good for is comparison — knowing that running costs roughly twice as much per minute as brisk walking is solid, even if neither absolute value is precise.
Excess post-exercise oxygen consumption, or EPOC, is real: your metabolism stays slightly elevated after hard training. It is also routinely oversold. For typical sessions it accounts for roughly 6 to 15% of the calories burned during the workout, and it is only meaningful after genuinely intense or long efforts. It does not turn a 300-calorie run into a 600-calorie one. The larger long-term effect of resistance training is the lean mass you keep, not the hours immediately afterwards.
This calculator applies published population averages to your weight and duration. It cannot measure your actual oxygen consumption, cannot see your terrain or intensity variation within a session, and is not a clinical tool. If you are managing a heart condition, are pregnant, or are returning from injury, exercise intensity is a conversation for your clinician rather than a MET table.
Most consumer devices report gross calories and often use proprietary models tuned to be generous. If your watch says 450 for the run above and this page says 305, the honest answer is that neither is measured — but the MET figure is at least traceable to published data.
Rarely, because the arithmetic is unkind. A 305-calorie run is undone by a single large muffin. Exercise is superb for health, cardiovascular fitness, mood and preserving muscle; for changing body weight, intake is the larger lever.
Yes, and it adds up more than people expect. Non-exercise activity — walking, standing, fidgeting, housework — often accounts for a bigger share of daily expenditure than a single gym session.
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