The formula
How to calculate calories burned
This estimates calories burned during an activity from its MET value — a standard measure of how many times resting metabolic rate an activity demands — combined with your weight, how long you did it, and how hard you pushed.
MET values come from research compendiums that tested large groups of people, so the figure used here is a population average, not a measurement of you specifically. Multiplying by your weight and the standard MET-to-calorie conversion (× 3.5 ÷ 200 per minute) gives a reasonable estimate, but the intensity multiplier is a rough adjustment, not a lab-measured value.
What to enter:
- Weight (kg)
- Activity — moderate-intensity MET value for the activity, standard compendium approximation
- Intensity
- Duration (minutes)
- Distance (km) — optional — only used for the "calories per km" figure; leave at 0 to skip
The result updates on every keystroke. The URL updates too, which makes the filled-in version easy to bookmark or send to someone else.
The order the fields are filled in makes no difference to the result — the calculator recomputes the whole formula from whatever is currently in every field, not step by step. That means it is safe to adjust one number, watch the result change, and adjust it back, without worrying about resetting anything first.
Why calories burned matters
The formula behind calories burned is standard and has not changed in decades; what changes is the situation it gets applied to. Two households can run the identical calculation and land on very different conclusions once their own numbers — income, rate, term, balance — are dropped in, which is why a generic textbook example is less useful than a calculator you can adjust to match your own circumstances.
It is also useful as a sense check before signing anything. A quote, an offer letter or a spreadsheet from someone else can contain an error, an optimistic assumption, or simply a different convention for rounding — running the same inputs through an independent calculator is a quick way to confirm a number before relying on it.
It is also worth being clear about what a single figure like this can and cannot settle on its own. It answers the specific question the formula was built to answer, and nothing more — a favourable calories burned result does not automatically mean a decision is a good one overall, since plenty of other factors that a formula cannot capture, from personal circumstances to how comfortable a commitment feels, usually matter just as much as the arithmetic. Use the number as one solid input among several rather than the whole of the decision.
In practice, most people arrive at a page like this one having already tried a version of the calculation by hand or in a spreadsheet, and use the calculator here to confirm it rather than replace it. That is a reasonable way to use it — the two should agree to the last decimal place if the same inputs and the same formula are used, and if they do not, the formula shown above is the one to check your own working against first.
Worked example
Work through the defaults on this page:
- Weight: 70 kg
- Activity: running
- Intensity: moderate
- Duration: 30 minutes
- Distance: 0 km
That gives:
- Calories burned: 360 kcal
- Calories per hour: 720 kcal/hour
- Calories per minute: 12 kcal/min
- Calories per km (if distance given): 0 kcal/km
These figures are only the calculator's own starting values, included so the working is visible rather than hidden inside the tool above. Replace them with your own numbers and the same arithmetic applies — nothing about the method changes, only the inputs feeding it.
Reading the result
Treat the result as a ballpark figure for planning, not a precise energy-expenditure measurement. It scales linearly with weight and duration, so doubling either one doubles the estimate — useful for comparing activities, less useful for exact calorie budgeting.
Where this goes wrong. Individual differences in fitness and movement efficiency can shift real calorie burn by 20-30% in either direction from the MET-based estimate — a trained athlete typically burns less than this estimate for the same activity because they move more efficiently, while a beginner often burns more.
A useful check on any unfamiliar result is to compare it against a rough mental estimate first — round the inputs to convenient numbers and see whether the calculator's answer lands in roughly the same territory. A wildly different figure usually means one of the fields was entered in the wrong unit, most often a percentage typed as a whole number where a decimal was expected, or the reverse.
MET stands for metabolic equivalent of task — one MET is the energy used sitting quietly. An activity with a MET of 7 uses roughly seven times as much energy as resting. MET values in this calculator come from standard exercise compendiums and represent moderate-intensity averages for each activity.
The intensity multiplier adjusts the base MET value up or down to reflect how hard you actually worked — a vigorous run burns meaningfully more per minute than a light jog of the same activity type, even though both are labeled "running."
It returns calories burned. With 70 kg weight, 30 minutes duration and 0 km distance, that comes to 360 kcal. Change any field and the figure moves with it.
Whenever one of the underlying figures changes — a new interest rate, a different balance, an updated term — since the result only reflects what is currently in the fields. There is no need to keep a separate record of past results; the web address for a filled-in version already carries the figures used to produce it.
Not unless a tax rate or a fee is explicitly one of the inputs above. Where it is not, the figure shown is a gross calculation, and any tax due depends on your personal circumstances and current tax rules, which are worth checking separately.
The arithmetic itself is exact — the calculator applies the formula shown above precisely, with no rounding until the final figure is displayed. The uncertainty, where it exists, is entirely in the inputs: an estimated rate or an approximate balance carries that same approximation through to the result.