The Short Answer: About 1 Calorie per Kg per Km
If you want a number you can do in your head, running burns roughly 1 net calorie per kilogram of body weight, per kilometer. A 70 kg runner burns about 70 net calories per km, or about 113 per mile. Multiply by your distance and you're within a rounding error of what any lab would tell you.
The calculator above is more precise, because it accounts for incline and reports both gross and net, but the rule of thumb is a good sanity check. If a gadget tells you a 3-mile run torched 600 calories, be suspicious. That would be double the real figure for most runners.
Why Pace Barely Matters (For a Fixed Distance)
This is the counterintuitive part. Running a mile costs about the same energy whether you jog it in 11 minutes or race it in 7. You're moving the same body the same distance against the same gravity. Faster running burns more calories per minute, but you finish sooner, so the totals nearly cancel out.
Where speed helps is time-limited. If you only have 30 minutes, running faster covers more ground, and more ground is more calories. But mile for mile, don't expect a hard effort to burn dramatically more than an easy one. That's also why easy mileage is the backbone of most training. It builds fitness and burns real calories without the recovery cost of hard running.
Gross vs Net: Which Number to Use
Two ways to count:
- Gross calories are everything your body spent during the run, including the baseline metabolism you'd have burned just sitting there.
- Net calories subtract that resting baseline. It's the honest "extra" the run cost you.
If you're tracking a calorie deficit for weight management, use net. Your daily maintenance number already counts the resting portion, so counting gross would double-dip. If you just want to know how hard the run worked your system, gross is fine. The calculator shows both.
The Math (ACSM Energy-Cost Formula)
The calculator uses the American College of Sports Medicine's gross VO2 formula for running:
VO2 (ml/kg/min) = (0.2 × speed) + (0.9 × speed × grade) + 3.5Speed is in meters per minute, and grade is incline as a decimal. The 0.2 term is the cost of covering flat ground, the 0.9 term is the extra cost of climbing, and the 3.5 is your resting oxygen use (one MET). From there:
- Convert your pace to speed in m/min.
- Compute VO2 at that speed and grade.
- Convert oxygen to energy at about 5 kcal per litre of O2, scaled by your body weight and the run's duration. That's gross calories.
- Subtract the resting portion (the 3.5 term) to get net calories.
It's a population average, so treat the output as a solid estimate, not a measurement. Individual running economy varies by 5 to 15 percent, and that's before you get into the disagreement between watches, chest straps, and treadmill consoles.
Calories Are a Byproduct, Not the Plan
Chasing a calorie target run to run is a fast way to burn out or get hurt. The runners who keep the weight off and hit their race goals are the ones who train consistently, and consistency comes from a plan that survives real life. See the VDOT calculator for setting the right training paces, the pace calculator for goal splits, and the full set on the running calculators hub.