It’s not the sexiest part of fitness, but if you want to build muscle, lose weight, or improve performance, knowing your daily calorie needs isn’t an option, it’s a requirement.
The calories needed to achieve your fitness goal are based a number of factors, including lifestyle, current fitness level, and genetics. All of these variables differ between individuals, and this is why it is essential to have your own customized number for your daily calorie needs.
Three Ways to Determine Your Calories
There are three ways to determine how many calories you should eat each day:
The first is the Harris-Benedict equation. It is the oldest and most reliable formula for calculating your daily caloric intake. It is still used by most medical experts today.
Next is a revised version of the Harris-Benedict formula with the same name as a famous 1984 study by Mifflin-St Jeor. While effective for determining caloric intake, studies show there is no significant difference between the two leading calorie equations.
Finally, you can simply use an online calorie calculator. Enter your gender, weight, and activity level, and you’ll be provided with your daily calorie needs. While efficient, some generic online calorie calculators might be based on unproven equations, potentially making them unreliable. If you’re going to use an online calorie calculator, look for one using the Harris-Benedict or Mifflin-St Jeor equations.
If you want a personalized daily caloric intake, I recommend using the Harris-Benedict equation.
How to Calculate Daily Calorie Needs
The Harris-Benedict formula relies on calculating two numbers: your basal metabolic rate, or BMR, and your total daily energy expenditure, or TDEE.
- Basal Metabolic Rate (BMR): The number of calories that you need within one full day to maintain your current weight. It does not factor in your level of physical activity.
- Total Daily Energy Expenditure (TDEE): The number of calories that you can realistically assume you’ll burn based on your current physical activity level. This includes how much you move throughout the day at work, at home, and the gym.
In order to calculate your BMR, TDEE, and caloric intake, you’ll need to collect the following information:
- Gender
- Weight
- Height
- Age
- Activity Level (use the guide below)
Activity Level Guide
Consider your current activity level, including your work life, and select the option that best suits you.
Sedentary: You are not active outside of daily necessity. You have a job that requires sitting for long periods of time.
Light Exercise (1 to 3 days per week): Outside of work, you engage in light activities such as walking, biking, or light resistance training.
Moderate Exercise (3 to 5 days per week): Your job involves some physical activity such as walking, and you visit the gym several times per week for cardiovascular and/or resistance training.
Heavy Exercise (6 to 7 days per week): You have a physically-demanding job (e.g., waitress, construction worker, or personal trainer), and you perform intense exercise several times per week.
Hardcore Exercise (daily): Your job requires constant physical activity, and you are in the gym performing intense workouts, sometimes twice a day. This is a category for athletes, fitness class instructors, and busy personal trainers.
Step One: Calculating Your Basal Metabolic Rate
Using the information from above, you will figure out the number of calories your body needs right now in order to maintain its current weight. You’ll use one of the following equations to calculate your BMR:
- Female = 655.1 + (4.35 × weight in pounds) + (4.7 × height in inches) – (4.7 × age in years)
- Male = 66 + (6.2 × weight in pounds) + (12.7 × height in inches) – (6.76 × age in years)
Step One Example: Tommy is a 24-year-old male. He is 5’ 8” (68 inches) and weighs 135 pounds.
- Male = 66 + (6.2 × weight in pounds) + (12.7 × height in inches) – (6.76 × age in years)
- 66 + (6.2 X 135) + (12.7 x 68) – (4.7 x 24)
- 66 + (837) + (864) – (113) = 1,654 calories
Tommy’s BMR (basal metabolic rate) is 1,654. He should eat 1,654 calories per day to maintain his current weight without factoring in his physical activity level.
Step Two: Calculating Your Total Daily Energy Expenditure
Now that you have your BMR, let’s determine your total daily energy expenditure. What level of activity best reflected your daily routine from the guide above? Find it in the chart below, then multiple your BMR by the suggested number.
Activity Level 1:
- Sedentary – Little or no exercise
- TDEE = 1.2 x BMR
Activity Level 2:
- Light exercise (1 to 3 days per week)
- TDEE = 1.375 x BMR
Activity Level 3:
- Moderate exercise (3 to 5 days per week)
- TDEE = 1.55 x BMR
Activity Level 4:
- Heavy exercise (6 to 7 days per week)
- TDEE = 1.725 x BMR
Activity Level 5:
- Hardcore exercise (Daily)
- TDEE = 1.9 x BMR
Step Two Example: Tommy has a basal metabolic rate (BMR) of 1,654. He works in retail so he’s on his feet a lot. He also exercises three days per week. Tommy will use Activity Level 3.
- Tommy’s Total Daily Energy Expenditure (TDEE) = 55 x BMR (basal metabolic rate)
- 55 x 1,654 = 2,563 calories
- Tommy will have to eat between 2,500 and 2,600 calories each day to maintain his weight at his current fitness level.
Step Three: Adjust for Your Fitness Goal
Think about your fitness goal. Do you want to lose weight or gain muscle mass? You’ll need to adjust your TDEE to fit your personal goal.
Fat Loss: If weight loss is your goal, you’ll need to cut calories from your daily intake by 12%. Use the number from the TDEE equation and reduce it by 12%.
Fat Loss Example: Tommy’s TDEE is 2,500 calories, and he wants to lose weight.
- 2,500 calories x 12%
- 2,500 x .12 = 300
- 2,500 – 300 = 2,200
- Tommy needs to eat 300 fewer calories—a total of 2,200 calories—each day to support fat loss.
Muscle Mass: If you want to gain muscle mass, you’ll need to increase your caloric intake by 15%. Take your TDEE number and increase it by 15%.
Muscle Mass Example: Tommy’s TDEE is 2,500 calories, and he wants to increase his muscle mass.
- 2,500 calories x 15%
- 2,500 x .15 = 375
- 2,500 + 375 = 2875
- Tommy needs to eat 375 more calories each day – a total of 2,875 calories – to support muscle building.
That’s it! You now have your own personalized caloric intake. Plug this number into an app such as MyFitnessPal and track your meals to ensure you reach your caloric intake every day.
Readjust When Needed
You haven’t seen the last of the Harris-Benedict equation. You’ll use this equation again to calculate a new caloric intake once you reach your current goal or change your activity level. I’d recommend recalculating your caloric intake once every two to three months based on your progress.
Were You Able to Calculate Your Daily Calorie Needs?
If not, where did you get stuck? If you were successful, when will you begin using your new recommended caloric intake? Let me know in the comments below.