What formula does this use?

It uses the ACSM running metabolic equation, which estimates oxygen uptake from running speed and gradient, then converts oxygen to calories at about five kilocalories per litre of oxygen. This scales correctly with speed, unlike a single fixed kcal-per-mile rule.

What is the difference between total and net calories?

Total calories are everything you burned during the run. Net calories subtract what you would have burned at rest over the same time, giving the extra cost of the run — the figure that matters for energy balance and weight management.

Does running faster burn more calories?

For a given distance, faster running burns slightly more total energy because of higher oxygen cost, but the dominant factor is the distance and your bodyweight. Roughly, energy is close to one kilocalorie per kilogram per kilometre on flat ground.

How does gradient change the result?

Running uphill raises the oxygen cost sharply, so a positive grade increases calories burned. The ACSM equation adds a term proportional to speed multiplied by gradient to capture this.

Is the estimate accurate for walking or very slow jogging?

The ACSM running equation is most accurate at jogging speeds and above. For walking or very slow shuffling it can overestimate, because walking uses a different, separate metabolic equation.

Running Calories Burned Calculator

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Know what your run actually cost

Calorie estimates on watches and treadmills are often wildly inconsistent because many rely on crude fixed rules. This calculator uses the same equation exercise physiologists use — the ACSM running formula — which scales properly with your speed, your weight, and the gradient you ran. The result is a defensible estimate of both the total energy you spent and the extra energy beyond simply resting.

How it works

The tool first estimates the rate of oxygen uptake from your running speed and the gradient, using the ACSM running equation:

VO2 (ml/kg/min) = 0.2 * speed(m/min) + 0.9 * speed(m/min) * grade + 3.5

Oxygen uptake is converted to energy at roughly five kilocalories per litre of oxygen, then scaled by your bodyweight and the run duration (derived from distance and pace):

kcal/min   = VO2 * mass(kg) / 1000 * 5
total kcal = kcal/min * durationMin

Finally it subtracts the calories you would have burned at rest over the same time to give net calories — the honest figure for energy balance.

Example and notes

A 75 kg runner covering 10 km on flat road burns close to 750 total calories, of which a little under 700 is net once resting metabolism is removed. Notice how weight dominates: a heavier runner burns proportionally more over the same route. Trail, sand, wind, and heat all raise the real cost above this baseline, and uphill segments add substantially through the gradient term. Because the equation is calibrated for jogging and faster, treat estimates for walking pace with caution.