Calories burned running
Per kilometre and per session, net of resting energy — and the fact that the per-kilometre cost hardly moves with pace, which is the thing the 100-calories-a-mile rule gets wrong.
350kcal
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- Gross, including resting
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- Resting over the same time
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- Net per km
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- Net per kg per km
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- Speed
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- MET used
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- Walking the same distance
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Roughly ±10–15% on the flat, wider on hills and for new runners, whose running economy is poorer than the equations assume. The afterburn is small — oxygen consumption is back near resting within about fifteen minutes — so do not budget a meal around it.
Why "100 calories a mile" is wrong in two directions
It is the most repeated figure in running and it ignores the only input that really matters: your weight. Running costs roughly one net calorie per kilogram per kilometre. A 55 kg runner and a 95 kg runner covering the same 10 km differ by nearly 400 calories. The rule of thumb was built for someone around 70 kg and quietly applied to everyone.
It is also a gross figure dressed as a net one. The number worth adding to your day is net — what the run cost above the energy you would have spent anyway. That is also what Apple Health records as active energy, which is why the figure on your watch is smaller than the one on most websites.
Pace barely changes the cost per kilometre
This surprises people. Run a kilometre slowly or quickly and the energy cost is roughly the same — you are moving the same mass the same distance, and running economy does not vary enormously with speed. What changes is the cost perminute, which is why a fast run burns more in half an hour than a slow one does.
The page shows net calories per kilogram per kilometre precisely so you can watch it stay near 1.0 as you change the pace. The comparison with walking the same distance is the other half of the story: walking is cheaper per kilometre, not merely slower.
Gradient, and treadmill versus road
With a gradient set, the page uses the ACSM running equation, which models the vertical work separately from the horizontal. The vertical coefficient differs by setting: the treadmill value is 0.9, while running up a real hill costs about double that, so the toggle above is not cosmetic. Descents are treated as flat, because the equations do not model the saving well.
What about the afterburn?
Excess post-exercise oxygen consumption is real, and it is small. After a steady run, consumption is back near baseline within roughly a quarter of an hour, which is tens of calories, not hundreds. It is larger after genuinely hard interval work, and still not large enough to plan a meal around. Anything claiming a run keeps burning for a day is selling something.
How this fits a deficit
A 5 km run is around 300 net calories for most people — real, repeatable, and smaller than most runners assume when they are deciding what to eat afterwards. Running earns its place in weight loss through what it does to appetite, mood, and the habit of showing up, more than through the arithmetic. Thedeficit calculator is where the intake side gets decided.
Build up gradually, and if you have been sedentary or have cardiac risk factors, see a clinician before starting. General information, not medical advice.