Harris-Benedict Calculator (TDEE & BMR)
Calculate TDEE & BMR using the Harris-Benedict equation.
Calculated TDEE:
| Activity Level | Calories |
|---|---|
| Basal Metabolic Rate (BMR) | |
| little to no exercise | |
| light exercise 1-3 times per week | |
| moderate exercise 3-5 times per week | |
| heavy physical exercise 5-6 times per week | |
| heavy physical exercise 6-7 times per week |
Calculated BMI
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How to Calculate BMR & TDEE Using the Harris-Benedict Equation
Basal metabolic rate, or BMR, is also known as resting metabolism. This is the energy that your body uses to function when completely at rest. Even when you aren’t actively engaged in physical activity, your body still uses energy (AKA calories) to keep your body running.
So, BMR includes all your normal physiologic functions, such as respiration, heart rate, blood flow, and brain activity.
BMR is Based on Biological Makeup
Everyone has their own individual BMR based on their unique physiological and biological makeup. The only way to determine your true BMR is to have your metabolic rate measured by lab analysis through either direct or indirect calorimetry.[2]
These labs measure the heat coming from your body, which correlates to the number of calories you burn at rest.
Unfortunately, there are limitations to indirect calorimetry, such as cost and accessibility, which make it difficult for most people to do or even consider.[2] However, you can still calculate your BMR using predictive equations that rely on height, weight, age, and gender.
How to Calculate BMR
BMR is based on height, weight, age, and gender. These factors play a role in how much energy your body uses at rest.
For example, as far as gender goes, men tend to have more lean muscle mass than women. In general, this gives them a higher basal metabolic rate. Taller individuals or those who weigh more have a larger body mass, and therefore have higher BMRs as well.
Harris-Benedict Equation
The first formula created to calculate BMR was the Harris-Benedict formula. The equation was derived in 1919 and is still one of the most widely used BMR formulas.[3] There are two separate equations for men and women.
Men:
BMR = 66.5 + (13.75 × weight [kg]) + (5.003 × height [cm]) – (6.775 × age [years])
Women:
BMR = 655.1 + (9.563 × weight [kg]) + (1.850 × height [cm]) – (4.676 × age [years])
If you are using imperial units, you can easily convert between pounds to kilograms and inches to centimeters. To convert pounds to kilograms, divide the weight in pounds by 2.2. To convert inches to centimeters, multiply inches by 2.54.
For example, take a 25-year-old, 6-foot-tall (72 inches) male that weighs 180 pounds. His weight in kilograms would be:
72 inches × 2.54 = 182.88 cm
180 lbs ÷ 2.2 = 81.8 kilograms
You can then plug these values into the Harris-Benedict equation to calculate BMR:
BMR = 66.5 + (13.75 × 81.8) + (5.003 × 182.88) – (6.775 × 25) = 1,937 kcal
Thus, this individual has a BMR of roughly 1,937 calories.
Revised Harris-Benedict Equation
Over the years, the Harris-Benedict equation has gone through revisions to more closely approximate BMR. Based on more recent data, the following equation was derived:[4]
Men:
BMR = 88.362 + (13.397 × weight [kg]) + (4.799 × height [cm]) – (5.677 × age [years])
Women:
BMR = 447.593 + (9.247 × weight [kg]) + (3.098 × height [cm]) – (4.330 × age [years])
It was found that the revised formula predicts basal metabolic rate in healthy individuals with an accuracy of about ±14%.[4] So, while it is not perfect, it does help give an estimate of resting metabolism.
How to Calculate TDEE
As mentioned above, BMR is only your resting metabolism. The total amount of energy you burn every day also depends on how active you are.
Once you have used the Harris-Benedict formula to calculate your basal metabolic rate, you can calculate your total daily energy expenditure, or TDEE. TDEE is an estimate of the amount of energy, or calories, you burn daily when accounting for your activity level.
To calculate TDEE, you can simply multiply your BMR by an activity factor based on your average daily activity level. The following table shows the activity factor corresponding to various levels of exertion:[5]
| Level of Activity | Example | Activity Factor |
|---|---|---|
| Sedentary | Little to no exercise, such as a desk job with no additional physical activity | 1.2 |
| Lightly Active | Light exercise 1-2 days/week | 1.375 |
| Moderately Active | Moderate exercise 3-5 days/week | 1.55 |
| Very Active | Hard exercise 6-7 days/week | 1.725 |
| Extremely Active | Hard daily exercise and physical job or two times a day training | 1.9 |
For example, if the individual above was engaged in moderate exercise, you can multiply 1,937 calories by 1.55, resulting in a value of close to 3,000 calories for total daily energy expenditure.
Maintaining a Healthy Weight Using BMR and TDEE
Determining your calorie needs can be helpful for leading a healthy lifestyle and maintaining a healthy weight.
Your physical activity plays a big role in weight maintenance, as studies have shown that individuals are able to maintain substantial weight loss when they have high levels of total energy expenditure.[6]
Using a BMR or TDEE calculator can assist you in determining your daily calorie needs.
References
- Centers for Disease Control and Prevention, About Adult BMI, https://www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/index.html
- Delsoglio, M., Achamrah, N., Berger, M. M., & Pichard, C., Indirect Calorimetry in Clinical Practice, Journal of Clinical Medicine, 2019, 8(9), 1387. https://doi.org/10.3390/jcm8091387
- Bendavid, I., et al, The centenary of the Harris–Benedict equations: How to assess energy requirements best? Recommendations from the ESPEN expert group, Clinical Nutrition, 2020, 40(3), 690-701. https://doi.org/10.1016/j.clnu.2020.11.012
- Roza, A. M., & Shizgal, H. M., The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass, The American Journal of Clinical Nutrition, 1984, 40(1), 168–182. https://doi.org/10.1093/ajcn/40.1.168
- Kelly, M., Resting Metabolic Rate: Best Ways to Measure It—And Raise It, Too, American Council on Exercise, https://www.acefitness.org/certifiednewsarticle/2882/resting-metabolic-rate-best-ways-to-measure-it-and-raise-it-too/
- Ostendorf, D. M., Caldwell, A. E., Creasy, S. A., Pan, Z., Lyden, K., Bergouignan, A., et al, Physical activity energy expenditure and total daily energy expenditure in successful weight loss maintainers, Obesity, 2019, 27(3), 496-504. https://onlinelibrary.wiley.com/doi/abs/10.1002/oby.22373