Basal Metabolic Rate (BMR) is the amount of energy your body needs while in a restful state and its calculated using the Basal Metabolic Rate Calculator. When a person is resting, the nervous and the digestive systems become inactive, but the amount of energy needed to maintain vital organs in the body at that state is called the Basal Metabolic Rate (BMR). Note that an increase in your metabolic weight through things like exercise will increase your BMR value.
How to calculate BMR
Use the Basal Metabolic Rate Calculator to will quickly estimate your BMR value. Simply select either male/female, enter your age, weight (kg or lb), and your height (cm or in), then click “Calculate My BMR”.
Please note that that even the best accurate BMR calculators provide only a best guess and should only be used as a guide.
Basal Metabolic Rate Calculator Formula
Applying Mifflin – St Jeor formula which was established in 1990, superseding Harris Benedict’s 1919 to an individual’s BMR gives an estimate of the number of calories required per day to maintain a persons existing weight, based on the individual’s activity level. BMR is calculated differently for both males and females.
BMR for Men
The BMR for a male is calculated using the following formulas:
BMR (metric in kilograms & centimeters) = (10 × W) + (6.25 × H) – (5 × A) + 5
BMR (imperial in pounds & inches) = (4.536 × W) + (15.88 × H) – (5 × A) + 5
BMR for Women
The BMR for a female is calculated using the following formulas:
BMR (metric in kilograms & centimeters) = (10 × W) + (6.25 × H) – (5 × A) – 161
BMR (imperial in pounds & inches) = (4.536 × W) + (15.88 × H) – (5 × A) – 161
- W is the body weight in kg/lbs
- H is the body height in cm/inc
- A is the age of the person in years
Note that BMR decreases with the reduction of a person’s lean body mass. Generally, a person’s BMR decreases with age because people typically do not maintain lean body mass as they get older. Conversely, increasing one’s muscle mass will also appropriately increase his or her BMR value.
Total Calories Burned a Day Depending on Activity Level
With your BMR value, you can use it to calculate how much calories you burn on a daily basis depending on your activity level. This calculation is called Total Daily Energy Expenditure (TDEE). To calculate your TDEE, you simply multiply your BMR value by your activity level. The result will give you an estimate on the amount of calories needed to maintain your weight.
The Harris-Benedict equation is as follows:
BMR x activity level = TDEE (calories needed to maintain weight)
See below table that shows each activity level and its corresponding factor values:
Activity Level Description Formula Low (sedentary) You get little to no exercise (Desk Jobs) Calories Burned a Day = BMR x 1.2 Light You exercise lightly (1-3 days per week) Calories Burned a Day = BMR x 1.375 Moderate You exercise moderately (3-5 days per week) Calories Burned a Day = BMR x 1.55 High You exercise heavily (6-7 days per week) Calories Burned a Day = BMR x 1.725 Very High You exercise very heavily (i.e. 2x per day, extra heavy workouts) Calories Burned a Day = BMR x 1.9
For instance, a care worker who walks all week long and has a BMR value of 1520, would have an activity level of 1.725 depending on the duration of their job and work routine. Applying the formula, Total calories per day will be 1520 x 1.725 = 2622. What this value potentially means is if you want to main your body weight, you need to eat that much calories per day. Rather if you want lose some weight, you either eat less calories or increase your physical workout.
For more information about the Basal Metabolic Rate Calculator, see wikipedia.
What is a good BMR?
There isn’t any clear indicator for either a good BMR or a bad BMR. This would vary based on your body fat, daily calories intake and activity level. The average BMR for most men falls between 1,600 and 1,800 kcals per day, while most women’s BMR average around 1,500 kcals per day.
How does a low calorie diet affect the body
So lets break this down using a very simple example of a female aged 25 with a height of 5’4 and weighs around 120 pounds. First we calculate her BMR using Harris-Benedict’s formula ((4.536 × W) + (15.88 × H) – (5 × A) – 161). Her BMR result would be approximately 1275.
If her daily calorie intake is lets say 700 kcals and based on her BMR value of 1275 kcals, then her daily calorie intake falls short of what her body needs to continue to maintain her vital organs and this would potentially be dangerous.
A healthy female adult needs around 1500 kcals to maintain a healthy weight. So below is a breakdown of what happens when you eat less or more calories per day:
- Eat around 1100 kcals/day to lose weight
- Eat around 1600 kcals/day to maintain your weight
- Eat around 1200 kcals/day to gain weight
Also check out our BMI Calculator to calculate your body mass index value.