Running calorie calculator — kcal by distance & weight
Most of the energy cost of running comes from moving your mass over ground. That is why a simple weight × distance model works surprisingly well on flat roads — and why watches that over-trust noisy wrist HR often disagree with reality.
The core formula
We use kcal ≈ weight (kg) × distance (km) × 0.95 for flat running — close to the popular “1 kcal per kg per km” rule of thumb.
Optional elevation adds roughly 1 kcal per kg per vertical metre. A hilly 10K with 200 m gain meaningfully exceeds a flat 10K for the same weight.
Age, sex and genetics nudge efficiency, but for planning they are second-order. Weight and distance dominate.
Does running faster burn more?
Per minute, yes. Over a fixed distance, often almost no: the faster runner works harder but finishes sooner, so total energy is similar.
Example: 70 kg, 10 km in 40 vs 60 minutes — absolute burn stays near 665 kcal either way. Intensity efficiency (kcal/min) differs; total trip cost does not.
Where pace matters more: stop-start intervals, very technical trails, and when duration stretches resting metabolism (see net burn).
Absolute vs net calories
Absolute burn is what you expend while running. Net burn subtracts roughly what you would have burned resting for the same time (~100 kcal/h awake).
A four-hour marathon “costs” less net than the headline absolute number suggests — you would have burned ~400 kcal lying on the sofa anyway.
Watch apps sometimes mix these concepts. Prefer absolute for fuelling plans; net for rough weight-management math.
Why watches disagree
Optical HR on the wrist is often wrong in intervals and hills. Models that weight HR heavily can invent huge calorie swings that never happened.
GPS + weight models (like this tool) are calmer and usually closer for steady road runs. For trails, add elevation; for intervals, treat any number as ±15–20%.
FAQ
How many kcal per kilometre do I burn?
About 0.95 × your body weight in kg. A 70 kg runner burns ~66–67 kcal per flat kilometre.
Should I eat back all running calories?
Not automatically. Hard training needs carbs and protein for adaptation; chronic large deficits impair recovery. Fuelling quality beats chasing exact kcal.