MET Calories Calculator
Convert any MET value into energy — and interrogate the 3.5 constant behind it.
MET Calories Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- A MET is assigned to an activity, not a person, and takes no account of fitness, skill or mechanical efficiency.
- The 3.5 ml/kg/min convention derives from a single individual and overestimates resting uptake by roughly 35% in heterogeneous samples.
- Steady state is assumed, so interval and stop-start activities are systematically misrepresented.
- The 5 kcal per litre of oxygen conversion varies with substrate, from about 4.69 for fat to 5.05 for carbohydrate.
- Adult MET conventions do not transfer to children, who require the separate Youth Compendium.
In short: One MET is defined as 3.5 ml of oxygen per kilogram per minute, which is almost exactly 1 kcal per kilogram per hour. So 45 minutes at 8.0 MET for a 75 kg adult is 473 kcal gross, 413 kcal net. That 3.5 is a convention taken from one 70 kg man; Byrne (2005) measured a mean of 2.6, and substituting it drops the same session to 351 kcal — a 25.7% difference.
Formula
The chain is oxygen first, energy second. A MET multiplies the resting oxygen uptake; multiplying by mass and time gives litres of oxygen; each litre liberates about five kilocalories. Making RMR a variable rather than a literal is what lets you test the convention instead of inheriting it.
Worked Example
- Enter the MET value for your activity, or type any value you want to examine.
- Enter bodyweight and duration.
- Leave the resting constant at 3.5 for the conventional answer.
- Then set it to 2.6 — Byrne's measured mean — and read the difference.
- Use MET-minutes, not calories, when checking yourself against public-health guidance.
45 minutes at 8.0 MET, 75 kg: 473 kcal gross and 413 kcal net on the standard 3.5 constant. Switch the constant to Byrne's measured 2.6 and gross falls to 351 kcal — 25.7% lower, from one assumption, before any error in the MET value itself.
Strengths & Limits Of This Model
Where this engine is strong
- The resting constant is exposed and editable rather than hidden inside the formula
- Shows the full oxygen chain instead of an unexplained division by 200
- Reports MET-minutes, the unit public-health guidance is actually written in
- Quantifies how much of a calorie figure is assumption rather than measurement
Where it stops
- Requires you to already know or look up a MET value
- Carries no activity table by design — that belongs to the Calories Burned page
- Cannot model intervals or anaerobic work
- Steady-state assumption weakens badly for very long sessions
Practical Use Cases
Auditing a calorie figure you were given
A trainer or app quotes a number. Enter the MET they used and see whether it reproduces. If it does not, the difference is almost always gross-versus-net, an outdated Compendium value, or an undisclosed resting constant. All three are visible on this page.
Understanding why two calculators disagree
Run the same activity at 3.5 and at 2.6. The 25% swing you get from that single substitution is usually larger than the gap between the two calculators you were comparing, which reframes the disagreement as a shared assumption rather than a bug.
Checking yourself against the activity guidelines
Public-health targets are written in MET-minutes precisely so they do not depend on your bodyweight. Multiply MET by minutes, aim for 500-1,000 a week, and stop converting to calories, which reintroduces the bodyweight dependence the guideline removed.
Teaching the concept
The oxygen chain — MET to VO₂ to litres to kilocalories — is shown explicitly rather than collapsed into a single constant. For a student or a coaching client, seeing five kilocalories per litre of oxygen do the actual work makes the otherwise arbitrary 200 in the standard formula obvious.
Methodology & Editorial Standards
The calculation is built as an explicit oxygen chain rather than a single constant: VO₂ = MET × RMR, litres = VO₂ × kg × min / 1000, kcal = litres × 5. With RMR at the conventional 3.5 this reduces exactly to the familiar MET × 3.5 × kg × min / 200. RMR is exposed as a bounded input (2.0-5.0 ml/kg/min) so the reader can substitute Byrne et al. (2005) measured mean of 2.6 ± 0.4 and observe the sensitivity of every published calorie figure to that one inherited assumption. Intensity bands follow the CDC convention; MET-minutes follow WHO-aligned guidance.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
MET Calories Calculator — 20 Expert FAQs
20 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
What is a MET in exercise?
One metabolic equivalent is the oxygen cost of sitting quietly, conventionally 3.5 ml of oxygen per kilogram per minute. It is a ratio, so an 8 MET activity costs eight times resting energy. Because one MET is also about 1 kcal per kilogram per hour, the MET value doubles as an hourly energy cost per kilogram of bodyweight.
How do you convert MET to calories?
kcal = MET × 3.5 × kg × minutes ÷ 200. The 200 is not arbitrary: it is 1,000 ml per litre divided by the roughly 5 kcal released per litre of oxygen. For 45 minutes at 8 MET and 75 kg that gives 473 kcal gross. Subtract one MET to get the activity's own cost, 413 kcal net.
Is 1 MET really 1 kcal per kg per hour?
Almost exactly, and that is the useful coincidence. 3.5 ml/kg/min for 60 minutes is 210 ml/kg/hour, which is 0.21 litres per kilogram, which at 5 kcal per litre is 1.05 kcal per kilogram per hour. The 5% overshoot is why the shortcut runs slightly high against the formal calculation.
Why is the 3.5 ml/kg/min value criticised?
Because it came from one 70 kg 40-year-old man and was generalised to everybody. Byrne et al. (2005) measured a mean resting uptake of 2.6 ± 0.4 ml/kg/min in a heterogeneous sample, meaning the convention overestimates resting oxygen uptake by about 35%. This page lets you substitute the measured value and see the roughly 25% fall in the answer.
What MET value counts as vigorous exercise?
6.0 MET and above by the CDC convention, with 3.0 to 5.9 counted as moderate and 1.6 to 2.9 as light. Brisk walking at 4.8 is moderate; running at 6 mph is 9.3 and firmly vigorous. The thresholds are population conventions, so a very unfit person may reach genuinely vigorous physiological strain at a nominally moderate MET.
What are MET-minutes and why do guidelines use them?
MET-minutes are MET multiplied by duration — 45 minutes at 8 MET is 360. Guidelines use them because, unlike calories, they do not scale with bodyweight, so the same target applies to everyone. The WHO-aligned range is 500 to 1,000 MET-minutes per week.
Does a MET value account for my fitness level?
No, and this is its central weakness. The MET is assigned to the activity, not the person. Two people running side by side at the same speed are assigned the same MET even though the fitter one is working at a far lower fraction of maximum. Percentage of VO₂max or heart-rate reserve captures that; a MET cannot.
Can MET values be used for interval training?
Poorly. METs assume a steady state, and intervals are by definition not steady. Averaging a MET across work and rest understates the physiological cost of the hard bouts and ignores the anaerobic contribution entirely. For interval sessions, treat any MET-derived figure as a rough lower bound.
What is the highest MET value in the Compendium?
The 2024 Adult Compendium tops out around 23.0 MET for running at 14 mph. Values above roughly 20 are sustainable only by elite athletes for short periods. This page rejects entries above 25 because there is no published activity there and the result would be arithmetic without physiology behind it.
Why does my calorie number differ from the Compendium's?
Usually because of the constant. If a source reports gross energy on the 3.5 convention and you compute net on a measured 2.6, the two can differ by more than a third for the same session. Neither is a mistake so long as the assumption is stated — the problem is that it usually is not.
How many calories is 1 MET-hour?
About 1 kcal per kilogram, so a 75 kg adult spends roughly 75 kcal per MET-hour. A one-hour session at 8 MET is therefore near 600 kcal gross, which the exact formula refines to 630. The approximation is close enough for planning and wrong enough that you should not balance a diet with it.
Do METs work for swimming and water activities?
The Compendium lists them, but water adds thermal and buoyancy effects the MET does not model, and technique changes the cost of swimming more than almost any other activity. A skilled and an unskilled swimmer at the same speed can differ enormously in real oxygen cost while sharing one tabled value.
Should I use gross or net METs for weight loss?
Net, because your daily calorie target already includes resting metabolism. Logging gross exercise calories against a maintenance figure double-counts the resting component and quietly erases part of the deficit. The gap is proportionally largest for gentle activity, where much of the gross figure is simply being alive.
Is a higher MET always better?
No. Higher METs cost more energy per minute but carry more joint load, more recovery cost and lower adherence. Accumulated MET-minutes over a week predict health outcomes better than peak intensity, and a sustainable 4.8 MET walk performed daily beats a 12 MET session abandoned in February.
How accurate is the 5 kcal per litre of oxygen conversion?
It is a good average but it depends on fuel mix. Oxidising carbohydrate yields about 5.05 kcal per litre of oxygen and fat about 4.69, so the true figure drifts with intensity and diet. The roughly 7% spread between those endpoints is small next to the uncertainty in the MET value itself.
Can I use MET calculations for children?
Not reliably. The adult 1-MET convention does not hold for children, whose resting metabolic rate per kilogram is substantially higher, and a separate Youth Compendium exists for this reason. Applying adult MET values to a child systematically understates the relative cost of activity.
Is this met calories calculator free to use?
Yes. It is free, requires no account, and has no usage limits. ApexConverter is funded by contextual advertising, never by selling user data.
Is my data sent to a server?
No. The engine runs as Vanilla JavaScript inside your browser under our Zero-Server Client-Side Execution model. Your figures are computed locally and are never transmitted, logged, or stored.
How accurate is this calculator?
It applies the standard closed-form formula in IEEE-754 double precision, rounding only at the display layer. The engine is reconciled against an independent reference implementation before release.
Does it work on mobile?
Yes. The interface is mobile-first with numeric keypad hints and is tested down to a 320-pixel viewport with no horizontal scrolling.