Estimate the energy spent on your session using the MET method based on weight, duration and pace.
Estimate calories burned from weight, duration and intensity (MET method).
Compute calories burned while running based on weight, duration and pace (MET method).
MET method: kcal = MET × weight (kg) × duration (h). MET varies with pace (2011 Compendium of Physical Activities).
MET stands for metabolic equivalent of task, and it expresses the intensity of an activity relative to rest. One MET is your resting expenditure, about 1 kcal per kilogram of body weight per hour. Running at 6 mph (10 km/h) is worth roughly 10 METs, so ten times what you burn sitting still.
That gives a simple equation: calories = METs × body weight in kilograms × duration in hours. A 154 lb (70 kg) runner covering an hour at 6 mph burns around 700 kilocalories. Body weight scales the result directly, which is why two runners side by side never burn the same amount.
Several factors move the result significantly, and they explain why different apps disagree about the same run:
Over the same distance, running burns more than walking, but the gap is smaller than most people assume, on the order of 25 to 30 percent. Running a mile costs roughly 1.6 kcal per kilogram of body weight, walking the same mile costs about 1.2.
The real difference is time: in one hour a runner covers far more ground than a walker, so total expenditure ends up much higher.
For a 154 lb (70 kg) runner at a moderate pace, roughly 600 to 750 kilocalories. It climbs past 900 for a 200 lb (90 kg) runner or a fast pace, and drops below 500 for a lighter runner going easy. The calculator above gives an estimate matched to your own numbers.
Watches fold in heart rate, sometimes elevation, and a stored user profile, so they land somewhere other than a textbook MET calculation. No non-invasive method is exact: a 10 to 20 percent spread between two sources is normal. Stick to one method when comparing two of your own runs.
On a hilly course, yes, because the difference becomes material. A mountain run can burn half as much again as a flat run of the same duration. On flat roads, ignoring elevation changes almost nothing.
Running creates an energy deficit that contributes to fat loss, but diet remains the deciding factor: an hour of running is worth about one generous meal. Running also delivers cardiovascular and metabolic benefits that have nothing to do with the scale, and those alone justify the habit.