Simply stated, a BMR calculator is a tool or equation used to calculate your basal metabolic rate (BMR), or resting metabolic rate (RMR). When BMR is needed for medical reasons or to apply to scientific research, more complex methods may be employed to find it, including measuring oxygen consumption and carbon dioxide production, and rate of heat loss.^{1,2 }However, a simple formula can be used to calculate your own BMR at home, and there are many calculators online that apply this formula to your information for you. But what is BMR, and why should you care about it?

BMR stands for basal metabolic rate. Your basal metabolic rate (or resting metabolic rate) is the amount of energy you need to perform the basic bodily functions that keep you alive. This includes keeping your heart beating, your lungs breathing, your liver working, and even maintaining your muscles. By calculating your BMR, you find the number of calories you need to consume if you were to sit around and do nothing all day.^{3} Surprisingly, 60 – 75% of the calories you burn in a day are used to support your necessary functions. The rest of your calories are divided between digestion, and small activity such as walking from room to room.^{3} Knowing your BMR and how these calories are used can help you understand your own activity and eating habits, and help you to strategize to meet your fitness goals. Whether you want to lose fat, build muscle, or better understand how to maintain your current physique, knowing your BMR can help you make more informed decisions.

## How to Calculate BMR

There are many ways to calculate BMR. In medical or research centers, you’re likely to find machines that take complex physiological measurements of energy expenditure to feed into formulas. However, you can find a useful measurement of your BMR by simply plugging your information into a formula, or into online calculators to make the calculation for you. This formula considers gender, weight, height and age, and additionally assigns a value to your current activity level to give you an AMR, or active metabolic rate.^{3} Here, we have the formulas for both men and women so you can calculate your own BMR and AMR at home, or double check the numbers you get from online sources.

## BMR Calculator for Women

The formula for women to calculate BMR is as follows^{3}:

655 + (4.35 x weight in lbs) + (4.7 x height in inches) – (4.7 x age in years).

So, if you’re a 28-year-old woman who is 5’8” and 158 lbs, your equation would look like this:

655 + (4.35 x 158 lbs) + (4.7 x 68 in) – (4.7 x 28 years)

655 + (687) + (319) – (131) = 1,530 calories.

This means that on a day where all you do is lounge in bed, you’re burning 1,530 calories. The next step is to add your daily activity value to this number to get a more accurate reading of how much energy you burn during a regular day. Find your activity level in the list below, and multiply your BMR by its value:

If you rarely exercise = BMR x 1.2

If you exercise 1 – 3 days per week = BMR x 1.375

If you exercise 3 – 5 days per week = BMR x 1.55

If you exercise 6-7 days per week or have a physically demanding job = BMR x 1.725

Using the example above, if your BMR is 1,530 and you exercise 3 – 5 days per week, your active metabolic rate would be:

1,530 x 1.375 = 2,103 calories per day.

This is the number of calories you can consume in a day to maintain your current weight without changing anything – a good number to know if you’re in a good spot and don’t want to lose it!

## BMR Calculator for Men

The method to calculate BMR for men is the same as for women, except that the numbers used in the first formula are different to account for the general difference of body composition and makeup between men and women. The formula for men to calculate BMR is as follows^{3}:

66 + (6.23 x weight in lbs) + (12.7 x height in inches) – (6.8 x age in years).

For example, if you’re a 30-year-old man who is 6’2” and 200 lbs, your equation would look like this:

66 + (6.23 x 200 lbs) + (12.7 x 74 in) – (6.8 x 30)

66 + (1,246) + (939) – (204) = 2,047

This is the number of calories you need to consume if you were to sit around doing absolutely nothing all day. Just like above, the next step is to account for your regular activity level. The activity values are the same as for women:

If you rarely exercise = BMR x 1.2

If you exercise 1 – 3 days per week = BMR x 1.375

If you exercise 3 – 5 days per week = BMR x 1.55

If you exercise 6-7 days per week or have a physically demanding job = BMR x 1.725

So, if your BMR is 2,047 and you exercise 3 – 5 days per week, your active metabolic rate would be:

2,047 x 1.375 = 2, 814 calories per day.

This is how many calories you can consume at your current activity level to maintain your current weight.

## BMR Calculator to Lose Weight

Now that you know how to calculate your BMR and account for your current level of activity, how can this help you to lose weight? Weight loss, in the simplest terms, is an equation of calories in vs calories out. To lose weight, you must burn more calories (calories out) than you consume (calories in).^{4} Knowing your BMR helps you to pick a daily calorie goal based on your body’s specific needs.

A 500-calorie deficit is generally recommended for sustainable, healthy weight loss.^{3} To figure out your weight loss calorie goals, simply subtract 500 from your active BMR number. If we use the women’s example from above, her weight loss calorie intake should be:

2,103 (active BMR) – 500 = 1, 603 calories per day.

By cutting out 500 calories a day, you can expect to burn roughly 1 pound per week without changing your activity level.^{3} However, if your daily calorie goal drops to less than 1,200 for women or 1,800 for men by cutting 500 calories, cut less, as it is not healthy to cut below these numbers.

If you want to speed up your weight loss, try burning an extra 250 calories per day through exercise. This can boost your progress to up to half a pound every week without cutting more calories per day. Being too restrictive with your calorie intake can trigger your metabolism to run more slowly and preserve your fat stores – exactly the opposite of your goals.^{5} Also, body composition will have a greater effect on your weight loss, as muscle burns more calories when resting than fat.^{4} For some added support, try combining a strength training routine with a testosterone support supplement like HexoFire Labs Delta Prime.

### Sources Cited

^{1}Levine, J. A. (2005). Measurement of energy expenditure.*Public health nutrition*,*8*(7a), 1123-1132.https://doi.org/10.1079/PHN2005800^{2}Columbia University Center for Metabolic and Weight Loss Surgery (n.d.). Metabolic Analysis. Retrieved May 7, 2018 from http://columbiasurgery.org/conditions-and-treatments/metabolic-analysis. View link.^{3}Thompson, D Jr. (2010, May 26). Boost Weight Loss by Knowing Your BMR. Everyday Health. Retrieved on May 7, 2018 from https://www.everydayhealth.com/weight/boost-weight-loss-by-knowing-your-bmr.aspx. View link.^{4}Mayo Clinic (2017, August 30). Metabolism and weight loss: How you burn calories. Retrieved May 7, 2018 from https://www.mayoclinic.org/healthy-lifestyle/weight-loss/in-depth/metabolism/art-20046508. View link.^{5}Tremblay, S. (2017, July 18). How to Raise Your Basal Metabolic Rate. LiveStrong.Com. Retrieved May 7, 2018 from https://www.livestrong.com/article/258368-how-to-raise-your-thermogenic-basal-metabolic-rate/. View link.