The formula
How to calculate running calories
The energy cost of running depends almost entirely on how far you go and how much you weigh. Pace has surprisingly little effect on the total — running 10 km faster gets you the same calories in less time, not more calories.
The coefficient of about 1.036 kcal per kilogram per kilometre comes from treadmill studies of running economy. It holds well on the flat; hills, wind and soft ground raise it, and the effect of gradient is substantial.
Fill in the following:
- Body weight (kg)
- Distance (km)
- Time taken (minutes)
Everything recalculates as you type, and the numbers in the address bar update with it, so a link to this page carries your figures with it.
If an exact figure for one of the fields is not available, a careful estimate is a reasonable starting point, since the calculator recomputes instantly the moment a more accurate number is available — nothing here depends on getting every field exact on the first pass.
Why running calories matters
People usually look up a running calories calculation to put a number on something they can already sense but cannot quite quantify — how their fitness compares with a reference range, how a measurement is trending, or what a change actually means. A calculator turns that vague sense into a concrete figure, which is useful even though the figure itself is only ever an estimate.
Because the calculation depends on a formula rather than a device, it is useful anywhere a scale, a tape measure or a stopwatch is available, without needing specialist equipment — which is also exactly why it should be treated as an estimate rather than a clinical measurement.
A single number like this is most useful placed in context rather than read in isolation. Reference ranges exist because bodies vary considerably and still count as healthy across a wide spread of values, so a result sitting outside a commonly quoted range is a prompt to look more closely rather than a verdict on its own. The same figure, tracked consistently over time, tends to say more than any single reading ever will.
Where a result depends on more than one measurement, small errors in each input tend to compound rather than cancel out — a slightly mismeasured waist and a slightly mismeasured height, taken together, can shift a derived figure more than either error would on its own. Taking each measurement carefully, and ideally twice, is worth the extra minute it takes.
Worked example
Take the figures the calculator starts with:
- Body weight: 75 kg
- Distance: 10 km
- Time taken: 55 minutes
That gives:
- Calories burned: 777 kcal
- Net of what you would have burned resting: 705 kcal
- Calories per kilometre: 78 kcal
Those starting figures exist only to show the calculation working, not as a target or a reference value to compare yourself against — replace them with your own measurements in the calculator above and the same formula applies exactly as shown.
Reading the result
The net figure subtracts the calories you would have burned anyway while resting. It is the honest number for weight management, and it is typically 10–15% below the gross figure.
Where this goes wrong. Fitness watches and gym machines routinely overstate by 15–25%, because they estimate rather than measure. Treat any calorie figure as approximate, and be careful about eating back what a device claims you burned.
As with any general-purpose formula, the result here is an estimate derived from population averages, not a measurement specific to you — a reasonable starting point for a conversation with a qualified professional, not a replacement for one. Nothing on this page is medical advice.
Per kilometre, only marginally. Per hour, considerably — because you cover more ground. If total energy expenditure is the goal, distance matters more than pace.
For a 75 kg runner, roughly 390 kcal gross and around 350 net. Body weight is the main variable: a 90 kg runner burns about 20% more over the same distance.
The answer it gives you is calories burned. With 75 kg body weight, 10 km distance and 55 minutes time taken, that comes to 777 kcal. Change any field and the figure moves with it.
It uses a published formula applied exactly as defined, so the arithmetic itself is precise — but the formula is a population-level estimate, and individual results can vary from it for reasons the formula has no way to account for. Treat the output as a reasonable estimate rather than a measured or diagnostic value.
For most people, yes — a single reading is a snapshot, while the same measurement repeated consistently over weeks or months shows a trend, which is generally more informative than any one figure taken in isolation.
Small differences between calculators usually come down to which published formula or reference dataset each one uses — several equations in this area exist in more than one accepted version. This page states the specific formula used in the section above, so it is possible to check directly whether another source is using the same one.