BMR Calculator

BMR is short for Basal Metabolic Rate and represent the amount of calories your muscles burn every day just to maintain vital operations such as breathing or thinking. In other words BMR amount is the amount of calories your body would burn if you were to stay in bed the whole day and do nothing at all!

How to Calculate your Basal Metabolic Rate

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As previously discussed earlier within this section of our webiste, an individual's Basal Metabolic Rate (BMR) is the minimum number of calories required to sustain their life in a state of rest. In other words, an individual's Basal Metabolic Rate is the amount of energy (measured in calories) required by their body to perform all of its bodily functions while remaining asleep in bed all day.

The first step for any individual who has a fitness goal to lose or gain weight is to determine the total number of calories that their body burns per day. More specifically, an individual’s BMR value is the total number of calories their body requires for all normal bodily functions (excluding all activity factors).

Such bodily functions include keeping the heart beating, inhaling and exhaling air, digesting food, making new blood cells, maintaining body temperature and every other metabolic process that occurs within the body. An individual's BMR can account for burning as much as 70% of the total calories expended. While the BMR of an individual is the total number of calories that an individual burns while at rest over a 24-hour period, the total daily energy expenditure (TDEE) value takes into account their BMR value plus all of their physical activities as well.

An individual's TDEE level can be considered their personal maintenance level. By knowing the number of calories your body burns on a typical day, you can then design a weight loss program that is centered around your specific TDEE value. According to research conducted by exercise physiologists William McArdle and Frank Katch, the average maintenance level for women in the United States is 2,000-2,100 calories per day, and the average for men is 2,700-2,900 per day. Please note that these figures are only averages and can vary greatly. For example, there are triathletes that require a diet consisting of 6,000 or more calories per day just to maintain their current weight level.

There are several methods an individual can use to determine their TDEE value. These methods typically include factors such as age, sex, height, weight, lean body mass and activity level. The most accurate methods include taking into account an individual’s lean body mass. This article will discuss two of the most accurate methods that an individual can use to determine their specific TDEE value.

The first method discussed will be the Harris-Benedict formula, which is based on total body weight. In addition, the Harris-Benedict formula utilizes factors such as height, weight, age and sex to determine an individual's BMR. Once an individual's BMR level has been determined, it will then be necessary to calculate their specific TDEE value. This will be accomplished by multiplying their BMR value by their specific activity multiplier. It should be noted that the Harris-Benedict formula does not include an individual’s lean body mass. Because of this, the Harris-Benedict approach will be very accurate for all but the extremely muscular (will underestimate caloric needs) and the extremely overweight (will overestimate caloric needs).

The second method is the Katch-McArdle formula, based on an individual’s lean body mass. This approach can be taken by individuals that have had their body composition tested and know their lean body mass. This approach is more accurate than the Harris-Benedict approach since the Harris-Benedict approach is based on total body weight.

The Harris-Benedict Formula (BMR based on total body weight)

The Harris-Benedict formula utilizes separate equations for men and women. This is due to the fact that men generally have a higher level of lean body mass (LBM) than women, and this phenomenon is accounted for in the men's equation. Since the Katch-McArdle formula accounts for LBM, a single equation applies to both men and women.

BMR Formula (Standard English) BMR Formula (Metric)

Note: 1 inch = 2.54 cm., 1 kilogram = 2.2 lbs.

BMR Example

Subject: Female, 30 years of age, 5' 6" tall (167.6 cm), 120 pounds (54.5 kilos)

BMR Formula (Standard English)

Women BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) - (4.7 x age in years)

Calculated BMR: 655 + 522 + 310 - 141 = 1,346 calories/day

BMR Formula (Metric)

Women BMR = 655 + (9.6 x weight in kilos) + (1.8 x height in cm) - (4.7 x age in years)

Calculated BMR: 655 + 523 + 302 - 141 = 1,339 calories/day

NOTE: Although the standard English and Metric calculations yield a slightly different result, it is not statistically significant.