What is a MET?
One MET is your resting metabolic rate — roughly 1 kcal per kg of body weight per hour (the energy cost of sitting quietly). An activity rated 6 METs burns six times that. So a 70 kg person doing a 6-MET activity for 30 minutes burns:
6 × 70 kg × 0.5 h = 210 kcal
The MET values here come from the Compendium of Physical Activities (Ainsworth et al.), the standard reference used in research. Individual variation is real: fitness level, terrain, temperature and technique all shift the number ±20%.
Why the scale lies
Most gym machines over-report calories by 20–40% because they guess your weight and ignore efficiency. The formula above is honest but still an estimate — the only accurate way is a lab test. Use it as a planning tool: if you're trying to lose weight, the deficit matters more than the exact burn.
Compare activities
Running and jump rope top the chart per minute; walking is low per minute but easy to sustain for hours — daily steps add up faster than people think. Swimming and cycling are kinder on joints while still burning well.