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.
Here is what each field means:
- Body weight (kg)
- Distance (km)
- Time taken (minutes)
The result updates on every keystroke. The URL updates too, which makes the filled-in version easy to bookmark or send to someone else.
Consistency in how the underlying measurements are taken matters more than precision to the last decimal — measuring at the same time of day, in the same state of rest or hydration, makes readings taken weeks apart genuinely comparable in a way that a single very precise reading on its own is not.
Why running calories matters
The formula behind running calories comes from published research rather than being invented for this page, and it is presented here exactly as it appears in the literature it is drawn from — the value of a calculator is applying it correctly and instantly, not reinventing it.
This tends to get checked before or after a change in routine — a new training block, a change in diet, a different stage of a pregnancy — as a way of putting a figure on something that would otherwise only be felt rather than measured.
None of the figures produced on this page are intended to replace a proper assessment, and nothing here should be read as a diagnosis or a treatment recommendation. What a calculator like this is good for is preparation — arriving at an appointment with an actual number already in hand, rather than a vague sense of a change, tends to make that conversation more useful for everyone involved.
A calculator like this one is frequently used to prepare a specific number for an upcoming appointment, so that a description like "I think it has changed" can be replaced with an actual figure and a date it was measured on. Clinicians and trainers generally find a concrete number, however approximate, more useful to work from than a general impression.
Worked example
Here is the calculation with the starting values:
- 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.