A man and woman are running together.

Image Credit: dolgachov/iStock/Getty Images Your body’s energy comes in the form of calories. The more energy you need, the more calories you burn. Calculating how many calories you burn in a day must take into account your basal metabolic rate and your overall activity level. It must also factor in your exercise routines, which burn additional calories on the days that you work out.

  Advertisement
 
Basal Metabolic Rate

Your basal metabolic rate, or BMR, is the number of calories your body burns in one day to support basic body functions like respiration, circulation and immune system function. Calculation of BMR uses a person’s weight, height and age. Your BMR accounts for only about 60 to 75 percent of the total daily calories you burn because it does not include the calories expended in activities and exercise.

  Advertisement
 
  Video of the Day
  
Harris-Benedict Equation

The Harris-Benedict equation adjusts your BMR to reflect activity and exercise levels by multiplying BMR by one of a set of activity multipliers. The multipliers reflect varying levels of activity throughout a one-week period. If you are sedentary and do not exercise, multiply your BMR by 1.2. If you exercise lightly one to three times per week, multiply by 1.375. If you exercise three to five days per week, multiply by 1.55. For exercise six or seven days per week, multiply by 1.725; if you exercise seven days a week and also have a physically demanding job, multiply by 1.9.

  Advertisement
 
Use a Heart Rate Monitor

Heart rate monitors attach to your wrist and provide a real-time display of your heart rate. Because your heart rate can be used to calculate your rate of caloric expenditure, many monitors include calorie burn calculators. You can wear a heart rate monitor all day to determine how many calories you burn. A heart rate monitor takes into account any activities and exercises you engage in as well as your basal metabolic rate.

  Advertisement
 
  Advertisement
 
Higher or Lower Calorie Expenditure

The Harris-Benedict equation is still prone to error. Depending on your specific activity level and your metabolism, your caloric expenditure might be higher or lower than that obtained with the Harris-Benedict equation. If you work out several times a week in addition to your routine activities, you may burn additional calories. If you are trying to determine your calorie expenditure for weight loss or dietary reasons, talk to your doctor or nutritionist about your specific dietary needs before starting any diet or exercise plans.

  Advertisement
 
  Advertisement
  
  references
  
      Hussmanfitness: John's BMR Calculator
    
      Harvard Heart Letter: Calories Burned in 30 Minutes for People of Three Different Weights
    
      Cornell University: Basal Energy Expenditure: Harris-Benedict Equation
    
      Healthy Pac-Cats: Physical Activity and Controlling Weight
       




  references
  
      Hussmanfitness: John's BMR Calculator
    
      Harvard Heart Letter: Calories Burned in 30 Minutes for People of Three Different Weights
    
      Cornell University: Basal Energy Expenditure: Harris-Benedict Equation
    
      Healthy Pac-Cats: Physical Activity and Controlling Weight
    




A man and woman are running together.

Image Credit: dolgachov/iStock/Getty Images

Image Credit: dolgachov/iStock/Getty Images

      Hussmanfitness: John's BMR Calculator
    
      Harvard Heart Letter: Calories Burned in 30 Minutes for People of Three Different Weights
    
      Cornell University: Basal Energy Expenditure: Harris-Benedict Equation
    
      Healthy Pac-Cats: Physical Activity and Controlling Weight