The general formula for calories burned while running is as follows: Minutes spent running * (MET*3.5*weight in kg)/200.

If you do not know what your MET (Metabolic Equivalent of Task) is, use this formula to derive it: MET=[(0.2*Speed)+(0.9*Speed*%Grade)+3.5].

So if you ever want an extremely precise number of calories burned, then plug your numbers into that formula. When trying to do the calculations manually, remember to follow basic mathematical order of operations, PEMDAS (Parenthesis, Exponents, Multiplication, Division, Addition, and Subtraction).

If you want to save yourself time, instead of calculating it manually, use a treadmill calorie calculator. It uses the exactly the same formula to derive the number of calories burned. When trying to figure out how many calories you’ve ran on the treadmill, you will need four distinct variables: the grade (incline), how much time it took you to run the distance, your pace, and your weight. Let us discuss the four distinct variables one by one and talk about how they affect the amount of calories burned.

Time: Time spent running is positively correlated with increased calories burned. That means the more time you spend on the treadmill, the more calories you will burn.

Your Pace: The pace is the ratio of minutes per miles. Thus, the pace is ultimately how long it takes you to run each mile (or whatever unit the treadmill is set to). The pace is a factor in calculating your calories burned because it indicates how fast your heart is working. Obviously running 10 minutes per mile is going to burn more calories than running 15 minutes per mile.

Your Weight: Your weight heavily determines how many calories you burn. A 250 pound man will burn many more calories than a 150 pound man running the same distance (with all other things equal). How much does a 100 pound difference make? Well a 150 pound man will burn 657 calories running a pace of 6 miles an hour, at 60 minutes (and assuming a zero grade incline). However, keeping all factors the same but replace the 150 pounds with a man that is 250 pounds and you get 1,095 calories burned. Almost twice as much.