Methodology
How this calculator works
One formula, published research values, and honest labels. Here is everything that goes into your number — and everything that doesn’t.
The formula
Every estimate on this site comes from the standard MET equation:
calories = MET × weight (kg) × duration (hours)
Equivalently, with minutes: calories = MET × weight(kg) × minutes ÷ 60. The “200” comes from the convention that 1 MET ≈ 3.5 mL of oxygen per kg of body weight per minute, and roughly 5 kcal per litre of oxygen consumed.
Worked example. Running at a moderate pace (MET 9.8) for 30 minutes at 70 kg: 9.8 × 70 × 0.5 = 343 kcal. A 90 kg person doing the same session: 9.8 × 90 × 0.5 = 441 kcal. Time, intensity and body mass are the three dials.
What is a MET?
MET = metabolic equivalent of task. One MET is the energy you spend sitting quietly — by convention about 3.5 mL of oxygen per kilogram per minute. Brisk walking (~4 METs) costs four times that baseline; hard running (12+ METs) costs twelve times or more.
MET values come from the Compendium of Physical Activities, a research-reviewed catalogue of energy costs compiled by epidemiologists and exercise scientists. Where the 2011 corrected values exist, we use them. See the officialCompendium of Physical Activities databaseand the WHO overview ofphysical activity and energy expenditure.
Distance mode: pace becomes effort
For walking, running and cycling we store MET values at several speeds. When you enter a distance, we pick the nearest pace, compute the time it takes you (distance ÷ speed), then apply that pace’s MET to your weight. Faster paces carry higher METs, so a 5 km run burns more than a 5 km walk — by the math, not by marketing.
Worked examples
Want to check the math yourself? Open a specific activity and compare: arunning (moderate) estimate (MET 9.8), abrisk walking estimate (MET 4.3), or aswimming estimate (MET 7.0) — each page includes a full calorie chart by weight and duration, plus the calculator preloaded with that activity.
What this calculator does not model
- Body composition — muscle burns more than fat at the same weight.
- Fitness efficiency — trained athletes often burn fewer calories for the same output.
- Age and sex — smaller effects than weight; intentionally excluded to keep the method transparent.
- Terrain, weather, wind, incline, load — all shift real burn up or down.
- Temperature — heat and cold make the body work harder to regulate temperature.
- Diet and sleep — metabolism fluctuates with nutrition and rest quality.
- Afterburn (EPOC) — vigorous sessions keep burning after you stop.
Honest labelling: the conventional 1 MET baseline overstates resting oxygen use for many people by 20–30%, so MET estimates can lean optimistic. Use them to compare activities and track trends — not as clinical measurements.
Medical disclaimer
This tool provides general educational estimates only. It is not medical advice, diagnosis or treatment. Do not begin, stop or change an exercise program based on these numbers alone. If you have a chronic condition — especially cardiovascular disease, diabetes, hypertension or joint problems — or are pregnant, postpartum, or returning from injury, consult a qualified healthcare professional first. If exercise causes chest pain, faintness or severe shortness of breath, stop immediately and seek medical help.
Method FAQ
Why do MET values sometimes disagree between websites?
The Compendium publishes both original (1993) and corrected (2011) MET values, and some sites mix them or use older textbook numbers. We use the corrected values where available and stay consistent across every activity.
Does body fat vs muscle change the result?
Yes — muscle is more metabolically active than fat, so two people at the same weight can burn differently, especially at rest and during strength work. The MET formula uses total weight as a practical proxy; athletes and very lean people should treat estimates as directional.
Do I burn calories after the workout (afterburn)?
Vigorous exercise creates excess post-exercise oxygen consumption (EPOC) — a modest elevated burn for hours afterwards. The calculator counts activity-time energy only, so intense sessions likely underestimate your total daily impact.
Should I eat back the calories I burn?
That depends entirely on your goal and total intake. Many people overestimate exercise burn and undereat recovery fuel. Use the number as one input alongside a proper daily calorie target — not as a license to eat whatever you want.