BMR calculator | What is BMR | Equations to calculate BMR | BMR vs. RMR | How to use BMR calculator to lose weight or gain muscle | FAQs
The basal metabolism rate (BMR) is essentially the amount of energy/calories required to maintain the body at rest. BMR calculator is an excellent tool that helps you make more informed decisions to crush your fitness goals.
Your BMR is:
This is the number of calories your body needs to maintain basic functions such as breathing and circulation. It does not include the calories you need for physical activity or daily tasks.
What is BMR?
The basal metabolic rate (BMR) represents the minimum amount of energy needed to keep your body performing the most basic life-sustaining functions, such as breathing, circulating blood, and maintaining body temperature.
In other words, the BMR is your body’s energy requirement to fuel biological processes (i.e., respiration, digestion, cellular signaling, and mitochondrial activity) outside of the physical activity.
The BMR can be affected by various factors such as age, height, weight, amount of muscle mass, and hormones. It will vary from individual to individual and may also change as you get older.
Equations to Calculate BMR
There are several formulas you can use to calculate BMR . Here are two commonly used formulas:
- The Harris-Benedict formula:
- Men = 66.5 + (13.76 x weight in kg) + (5.003 x height in cm) – (6.755 x age in years)
- Women = 65.5 + (9.563 x weight in kg) + (1.850 x height in cm) – (4.676 x age in years)
- The Mifflin-St. Jeor formula:
- Men = (10 x weight in kg) + (6.25 x height in cm) – (5 x age in years) + 5
- Women = (10 x weight in kg) + (6.25 x height in cm) – (5 x age in years) – 161
Remember, these formulas estimate the number of calories you’ll burn at rest. The total number of calories you need to maintain your current body weight is referred to as “total daily energy expenditure” (TDEE).
You can use the TDEE calculator or calorie calculator to know your required daily calories to adjust your nutrition to hit your desired goal.
Note: It’s impossible to get exact TDEE since our activity level changes daily. Measuring in a laboratory setting is the most reliable way to get an accurate BMR.
BMR vs. RMR
The BMR stands for Basal Metabolic Rate, while RMR is Resting Metabolic Rate. Both can be used to calculate your body’s calorie needs to perform basic, life-sustaining functions.
The key difference between them is that your BMR calculates the number of calories you burn in 24 hours at rest, while RMR includes some bodily functions (i.e., the movement of light activities), such as eating, walking, using the restroom, stretching, etc.
Since the resting metabolic rate includes light activities, you’ll find the RMR slightly higher than your BMR.
How to Use BMR Calculator to Lose or Gain Weight?
First, calculate your BMR and then use the following equations according to your activity level to calculate your daily calorie need or TDEE:
- Sedentary lifestyle (little or no exercise): TDEE = BMR x 1.2
- Lightly active (light exercise/sports 1-3 days/week): TDEE = BMR x 1.375
- Moderately active (moderate exercise/sports 3-5 days/week): TDEE = BMR x 1.55
- Very active (hard exercise/sports 6-7 days a week): TDEE = BMR x 1.725
- Extra active (very hard exercise/sports & physical job or 2x training): TDEE = BMR x 1.9
The TDEE is the number of calories you need per day to maintain your current body weight.
To lose weight, consume 350-500 calories less per day than your TDEE. On the other hand, you’ll add this number of calories on top of your TDEE to gain weight and muscle mass.
For example, if your TDEE is 2300 calories, you’ll take about 1800 calories per day to lose weight and about 2800 calories to gain muscle.
Use the “body mass index” (BMI) calculator to know whether you are in the healthy or overweight zone so you can customize your training and nutrition plan to achieve your ideal healthy body weight.
What is a good BMR for my age?
Shortly, it depends from person to person, and it isn’t easy to set a standard BMR guideline for different age groups because the ideal BMR for a person depends on various factors, including age, gender, weight, height, and activity level.
However, men generally tend to have a higher basal metabolic rate than women due to their larger muscle mass and higher testosterone levels. Since we lose muscle mass and testosterone as we age, the BMR also follows a downward graph. 
Make sure you maintain healthy muscle mass in the body to prevent the decline in BMR. Incorporating resistance training into your routine can be an effective way to build and maintain lean muscle mass.
How to increase BMR?
Here’re some tips to increase your BMR:
1. Build muscle – Muscle tissue burns more calories than fat tissue when you’re at rest, so increasing your muscle mass can increase your BMR.
2. Exercise regularly – Doing physical activity regularly can increase BMR, especially resistance training.
3. Eat enough calories – If you consume fewer calories, your body may go into “starvation mode,” which can decrease your BMR. Make sure you’re eating enough to meet your daily energy needs.
4. Get quality sleep – Lack of sleep can lower your BMR. Try to get 7-8 hours of quality sleep every night.
5. Dring enough water – Dehydration can lead to a decline in BMR. Aim for 3-4 liters of water per day.
How to calculate calorie deficit with BMR?
To calculate your calorie deficit with your basal metabolic rate (BMR), follow these steps:
1. Calculate your BMR: You can use the above BMR calculator and give your age, weight, height, and gender to know your basal metabolic rate.
2. Determine your daily calorie needs or TDEE: To know how many calories you need per day to maintain your current body weight, multiply your BMR with a factor that defines your physical activity level. Follow the “How to Use BMR Calculator to Lose or Gain Weight” section above to know your daily caloric needs.
3. Deficite the calories: To lose weight/fat, you need to consume a calorie-deficient diet. The most sustainable and healthy amount of calories you can deficit is 500 calories per day. This means if your caloric need (i.e., TDEE) is 2300 per day, you’ll eat about an 1800 calories diet to lose weight. This will help you lose about 1 pound in a week (1 pound = 3500 calories, so 3500 calories/7 days = 500 calories/day).
Remember, daily calorie needs vary from person to person, and you should talk to a dietician or healthcare professional before making changes or adopting a new diet.