BMR CALCULATOR

Calculate Your Basal Metabolic Rate and Discover Your Daily Caloric Needs

Understand Your Body’s Metabolism with Our Accurate BMR Calculator

Find Out How Many Calories You Burn at Rest and Optimize Your Diet

Version 7.2.3 | Updated October 4th 2024

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Welcome to the most accurate macro calculator in the world!​

Join over 20,000 health-conscious individuals who trust our BMR Calculator every day, from fitness enthusiasts to personal trainers and even healthcare professionals. Be honest and precise when answering questions to make the most of our Accurate BMR Calculator – a reliable tool for understanding your body’s basic energy needs.

No more guesswork – just enter your details, select your activity level, and get your precise basal metabolic rate for better health and weight management. It’s the easiest way to understand your daily calorie needs and plan your nutrition effectively.

The more precise you are, the more accurate your results will be!

BMR_IIFYM

IIFYM BMR Calculator

It is no secret that IIFYM.com is the authority on flexible dieting. We help people burn fat and build muscle at an alarming rate. Our clients make amazing progress while eating the foods that they love, without the suffering that one might expect with a traditional fat-loss diet.

We have clients coming to us every day asking for help. When they do, one of the very first things we do is figure out their basal metabolic rate using our calculator for metabolic rate. If you want to succeed at making any sort of body composition changes, whether it’s to gain or lose weight, you need to know your basal metabolic rate.

BMR = Basal Metabolic Rate (similar to RMR = Resting Metabolic Rate, but for IIFYM and flexible dieting purposes, there is a distinction between the two).

Your BMR represents the number of calories your body burns at rest. The IIFYM calculator will calculate the precise amount of calories your body requires to keep you alive. At IIFYM, It starts with your BMR calculation, moves on to your TDEE, and ends with your fat loss macros.

Still confused about your BMR? Read on and I’ll explain it all to you!

So what is the basal metabolic rate and how does one figure it out? 

Let me share these details with you so that you get a better understanding of why it’s such an integral part of the process we use when working with clients.

If you’re like some of our clients, you decide to use a BMI calculator for weight loss or weight gain. (not to be confused with our BMR Calculator, for example)

This is unfortunate, however, as the BMI Calculator is not going to give you an accurate representation of how you’re doing.

What is Your BMR (Basal Metabolic Rate)?

Your basal metabolic rate is essentially the sum of all the energy your body uses each day to simply stay alive. Note this is not the number of calories needed to get you out of bed in the morning, to brush your teeth, or to cook the breakfast you’re eating on your IIFYM approach.

This is simply the energy required to keep your heart beating, your lungs taking in oxygen, your brain functioning, and all the other everyday tasks your body does to maintain life. 

As the name suggests, basal means fundamental. If you sat in bed all day long and didn’t move a muscle, this is how many calories you’d burn. This is the ideal way to figure out your calorie intake to lose weight

When we use this number with our clients then, we are figuring out this number. From here, this gives us a much better idea of how to formulate a fat-loss diet plan for them.

Please do keep in mind that no BMR calculator will be 100% accurate because your body is constantly changing on a day-to-day basis. 

If you are injured, for instance, your body will be working harder to help repair that injury and as such, you will be burning more calories because of it.

This said, if you use the right numbers, we’ve found that it’s accurate enough that you can then use it with other diet formulas to come up with a solid weight loss or muscle-building approach that will work incredibly well for 99% of the population.

Your BMR or basal metabolic rate is essentially the number of calories your body needs at rest or for minimal movement. 

Many people also confuse it with RMR (resting metabolic rate). However, a Resting Metabolic Rate calculator gives you the number of calories that you need without any movement.  RMR can give you a close estimate of your BMR.

How to Use IIFYM BMR Calculator

When looking for a calculator for metabolic rate, you are likely to come across a few different variations. We have found that the absolute best Basal Metabolic Rate results come from using the Mifflin-St Jeor equation. 

For this reason, we base our weight loss calculator on this formula. We’ve found through working with clients that other formulas, specifically the Harris-Benedict equation, which is another very commonly used BMI Calculator, overestimate the total calorie burn, and this can lead to stagnant progress.

We also like the fact that this equation doesn’t require you to know your body fat percentage, which we’ve found most of our clients do not know. Getting assessed for your exact body fat percentage to use in a diet plan can be a costly procedure depending on where you are located, so it’s best to use this same tool as effectively. 

Step#1: Enter Your Information in our BMR Calculator:

Our basal metabolic rate calculator considers your age, gender, size, and activity level to calculate the total number of calories your body needs or should consume per day.

Step#2:Adjust for Your Goal in the BMR Calculator:

Whether you want to lose weight or gain weight, you can customize the calculated number (BMR) to suit your fitness goals.  For example, if you’re wondering “How much calories should I eat to lose weight”, your goal should be to eat fewer calories than your BMR

Step#3:Things to Keep in Mind when using our BMR Calculator:

While our BMR calculator offers a valuable tool and can effectively guide you toward your health and fitness goals, remember that various factors can influence your calorie requirements. 

So, for personalized advice, consult a dietitian, or doctor or get in touch with our IIFYM coach who can customize your diet according to your health status and your fitness goals.

In summary, this Basal metabolism calculator calculates your daily calorie requirements depending on your details. Adjust it as needed to fit your weight goals. 

Why BMR is So Important?

If you want to lose, gain, or maintain weight, and need a good starting point, you should know your Basal Metabolic Rate. By determining your body needs with minimal movement i.e. your BMR, you can adjust your caloric intake accordingly. 

  • If you want to maintain your current weight, you should eat your BMR i.e. the number of calories your body needs at rest or for minimal movement.
  • If your goal is to gain weight, eat more calories than your BMR
  • Lastly, if you want to lose weight, eat fewer calories than your BMR

 Several factors can impact your BMR when you Calculate daily calorie requirements. These include:

  • Your physical activity level
  • Gender
  • Age
  • Existing health conditions or medications
  • Metabolism
  • Gut microbiome composition

 

While calorie counting or BMR provides you with a good starting point, it’s not the only factor that matters in your fitness journey. Many health professionals think that your dietary choices play a much bigger role.

That’s why, calculating only your Basal Metabolic Rate using a Basal calorie calculator may not provide the comprehensive information needed to design effective lifestyle changes for weight loss. 

Why do BMR and TDEE Matter?

So what do the results from our free fat loss tool tell us?? Why does it help with fat loss results?

The reason we feel getting a client’s results is so very critical is because it gives us a starting point to work off of.

Remember, to successfully lose body weight, you need to only accomplish one thing:

Eat fewer calories than you burn.

Notice I did not say, “Eat fewer calories than your BMR”. When calculating diet calories, we need to go off of your TDEE. This is the single most important number when it comes to the IIFYM weight loss plan.

An Important Distinction

Most of our clients come to us thinking that the numbers are where their diet starts. This could not be further from the truth, and we encourage you not to fall into the same trap that so many followers of IIFYM have before. 

As explained above, your Basal metabolic rate is the number of calories your body needs as a baseline. This does not include calories you burn during work, play, exercise, digesting food, or anything else. This data is only the number of calories your body needs, basically in a coma.

Once we calculate your daily calorie needs, we need to add to it the calories you burn through all of your activities throughout the day. This could be anywhere from 50% to 200% or more, to your requirement. When everything is totaled up, this number is called your TDEE calculator, and that is the number we back calories out of to trigger immediate fat loss with our clients.

So while eating fewer calories, it is important to know how few is too little or too many. This is where a BMR calculator and TDEE tool can be very helpful!

If you can do this, science has proven, you will start burning fat and losing weight at an immediate and predictable rate.

Likewise, if your goal is to build muscle mass, you again need to turn to a diet program that will figure out your BMR value, and then your TDEE after that. To build muscle, you need to take the opposite approach of losing fat. Building muscle requires that you consume more calories than you burn so that your body has something to build that muscle out of.

Until you provide the raw materials, you simply will not see success taking place. The calorie surplus in this case is an absolute must.

Of every single client that we have ever worked with, we have not come across even one who was able to consume more calories than they’ve burned off and lose weight. Science backs this up as well. Every study you look at showing fat loss results will indicate that the test subjects were eating in a calorie deficit.

This all comes down to the first law of thermodynamics – that energy cannot be created or destroyed. When you need the energy to fuel your daily activities and it’s not available from the foods you are eating, you’ll tap into stored body fat to provide that energy.

Likewise, if you consume more energy than your body burns off, that energy has to go somewhere. The result is that it gets converted into both body fat as well as muscle mass.

We stress the importance of this relationship to our clients so that they fully understand how seriously they need to take monitoring their calorie and best macro ratio intake as part of their flexible dieting approach.

Striking the right balance is crucial: how many calories should I eat a day calculator helps maintain this delicate equilibrium. If you’re wondering how to speed up my metabolism, understanding your maintenance calories becomes paramount. These numbers ensure that whether you aim to lose fat or build muscle, your approach aligns with your body’s needs and goals.

What is a Good BMR?

This can differ from person to person. Your BMR depends on involuntary bodily functions like breathing and blood circulation, you can do very little to lower or raise your BMR with your everyday activities. However, the simplest way to increase your BMR is to boost your muscle mass as muscle requires more energy to sustain. Consequently, having more muscle mass means burning more calories even at rest.

The total number of calories you burn in a day is known as TDEE or “total daily energy expenditure”. It depends on your BMR and your daily activity level. This number varies widely based on factors such as age, gender, and activity level.

To find your TDEE accurately, consider using our FREE TDEE calculator. However remember, that achieving a 100 percent precise BMR requires laboratory testing due to fluctuating activity levels every day. 

BMR Vs. RMR: What’s The Difference?

If you’ve been reading up on various fat-loss diets and fat-burning programs, chances are, you’ve heard of something called resting metabolic rate as well.

One of the most common questions we get from our clients looking for fast fat loss results is what the difference is between basal metabolic rate and resting metabolic rate.

There isn’t a great difference here, but your resting metabolic rate adds to your basal metabolic rate the calories burned during the process of digestion as well as light movements that don’t involve formal activities.

So, your resting metabolic rate or RMR will always be slightly higher than your BMR results. When we dial in our client’s macros, we prefer using a later as a baseline as we feel it gives us a better number to work from when figuring out the rest of the dietary numbers used in an IIFYM fat loss program

When it comes to metabolism, you might come across the terms BMR and RMR. so, what’s the difference between them? Let’s take a look: 

  • BMR, or Basal Metabolic Rate, refers to the energy your body uses for basic functions such as breathing, temperature regulation, and blood circulation. BMR is measured when you’re at complete rest.
  • On the other hand, RMR, or Resting Metabolic Rate is a broader term. It encompasses BMR but also energy factors used during processes like digestion and everyday movements (non-exercise) like dressing or eating.

In general, BMR and RMR are quite close so many people use them interchangeably, without any major harm. However, if you’re determining your energy needs for losing or gaining weight, it’s crucial to note whether calculations are based on BMR or RMR. Use the following guidelines:

  • If an equation specifies BMR, use our BMR calculator for an accurate estimate.
  • For equations based on RMR, opt for our dedicated RMR Calculator, which provides a slightly higher estimation.

 

In summary, while BMR and RMR are often used interchangeably due to their proximity, understanding their key differences will give you a more accurate estimate of your metabolic requirements for your health goals.

How to Gain Muscle or Lose Weight Using BMR?

Here’s how: 

  • Calculate your Total Daily Energy Expenditure (TDEE) using your BMR as a base by using our TDEE Calculator. 
  • Customize your nutrition plan accordingly to match your energy expenditure level.
  • Avoid the pitfalls of consuming too few or too many calories by basing your plan on precise calculations.

By utilizing your BMR to find your TDEE, you ensure your nutrition plan suits your energy needs. This will dramatically boost your efforts for muscle gain or weight loss.

BMR_Weight_Loss_IIFYM

BMR Calculator: How Do We Calculate Your BMR?

At IIFYM.com, we use the Mifflin-St Jeor equation, a widely acknowledged method known for its accuracy in calculating BMR for various individuals. Here’s a breakdown of the process:

BMR Formula for Men:

Men: BMR = 10 x weight (in kg) + 6.25 x height (in cm) – 5 x age (in years) + 5

BMR Formula For Women:

10 x weight (in kg) + 6.25 x height (in cm) – 5 x age (in years) – 161

Please note that the above calculations do not consider your activity level.

So, to calculate your daily calorie needs, we take into account your activity level because it gives a more accurate estimation of your nutritional requirements.

Activity IntensityDaily Calorie Needs
Minimal activity(Sedentary): Limited to no exercise2,060
Light exercise: 1-3 workouts/week2,361
Moderate exercise: 4-5 workouts/week2,515
Regular exercise: 3-4 intense workouts/week2,661
High-intensity exercise: 6-7 intense workouts/week2,962

Popular methods for calculating Your Basal Metabolic Rate (BMR):

Equations for BMR calculation include:

Mifflin-St Jeor Equation:

1. Mifflin-St Jeor BMR Formula For Men:

BMR = 10W + 6.25H – 5A + 5

Mifflin-St Jeor BMR Formula For Women:

BMR = 10W + 6.25H – 5A – 161

Revised Harris-Benedict Equation:

Harris-Benedict BMR Formula For Men:

BMR = 13.397W + 4.799H – 5.677A + 88.362

Harris-Benedict BMR Formula For Women:

 BMR = 9.247W + 3.098H – 4.330A + 447.593

Katch-McArdle Equation:

Katch-McArdle BMR Formula

BMR = 370 + 21.6(1 – F)W

In this equation:

  • W represents body weight in kilograms
  • H stands for body height in centimeters
  • A denotes age
  • F signifies body fat percentage.

BMR Variables: Factors That Affect Your BMR

Here are a few important  factors that can influence your Basal Metabolic Rate (BMR):

1. Muscle Mass:

Performing anaerobic exercises, like weight lifting, can indirectly boost your BMR by increasing muscle mass.  Muscle demands more energy at rest.

2. Age:

As you grow older, your BMR typically decreases due to changes in muscle mass and activity levels.

3. Genetics:

Your BMR can also be influenced by hereditary factors from your ancestors.

4. Weather:

Extreme temperatures, whether hot or cold, can affect your BMR. Cold environments raise it as your body works to maintain its temperature. On the other hand, excessive heat also increases BMR as your body tries to cool down.

5. Diet:

Regular, small meals can help boost your BMR. Conversely, starvation can significantly reduce it. Think of your body like a device in power-saving mode—it conserves energy when resources are scarce.

6. Pregnancy:

Pregnancy increases BMR as your body works to support the developing fetus. This usually leads to increased food intake. Menopause can also affect BMR due to hormonal changes.

7. Supplements:

Certain supplements, like caffeine, can temporarily raise your BMR and can result in weight loss.

In summary, your Basal Metabolic Rate (BMR) is influenced by factors such as muscle mass, age, genetics, weather, diet, pregnancy, and supplements.

BMR Calculator: What are the Limitations?

BMR_Limitations_IIFYM-1

While reliable BMR calculators are immensely helpful tools, they do have some limitations:

  • The Mifflin-St.Jeor equation, known for accuracy, can still be off by approximately 10% of your real Basal Metabolic Rate.
  • If you don’t consider your activity level, you won’t accurately calculate your daily calorie requirements, which could affect your health.
  • Lastly, although your BMR provides you important information about your body, it doesn’t show you a complete picture of your overall health and fitness. For example,it doesn’t take into account your muscle-to-fat mass, hormone levels, any underlying health condition, and many other important parameters of your health. 

So, while BMR calculators offer utility, they have limitations in accuracy and in providing a holistic view of health.

So, What exactly does your BMR tell you?

You might wonder what your BMR tells you. Well, it’s pretty straightforward:

  • Your BMR shows you the number of calories you burn while at rest, without considering your daily movements.
  • It serves as a baseline measure of your metabolism.

However, it’s just the most basic step in understanding your overall calorie needs. To find out your Total Daily Energy Expenditure (TDEE), you need to take into account your activity level:

  • Sedentary: 1.2
  • Lightly active: 1.375
  • Moderately active: 1.55
  • Very active: 1.725
  • Extra active: 1.9

To find your TDEE, you simply multiply your BMR by the activity factor. This figure gives you an estimate of the calories your body requires daily to maintain your weight. 

Summing Up Our BMR Calculator

All in all, it’s important to remember that the results you get are just a starting point. With our clients, we take the results and put them into another diet calculator to figure out the appropriate amount of carbs, proteins, and fats to help our clients reach their goals. Then from there, we make adjustments as time goes on.

You should always be adjusting your diet intake based on the real-world results you see. This is how we ensure that our clients always realize maximum fat loss results with their IIFYM protocol.

Your body is constantly changing and as such, your diet should be as well. A good BMR calculator is simply a starting point that helps you get to the results you want to see that much faster. To make the best progress, you really should check out our Macro Calculator

Ready to Transform Your Body?

Our IIFYM BMR Calculator is an easy to use yet powerful tool in your arsenal. Whether you want to lose fat, gain muscle, or find your perfect balance, this simple calculator gets you started right. Explore the variety of weight loss programs we offer, each designed to help you reach your goals more effectively.

Using the trusted Mifflin-St Jeor equation, it gives you accurate results fast. No more guesswork – just clear numbers you can rely on.

For those who are ready to take on a challenge, the Deadline Diet offers a structured plan with a clear timeline.

But we’re more than just numbers. We’re here to support you on your journey. With our guidance, you’ll reach your goals without giving up your favorite foods.

So why wait? Take the first step now. Calculate your BMR and realize your true potential. It’s time to make your dream body a reality. Let’s do this!

Start your journey today. Use our Basal Metabolic Rate Calculator and take control of your health and fitness. 

Ready for more? Check out our Macro Calculator to calculate your exact macros and by using a personalized approach, the Macro Blueprint helps you stay on track and reach your fitness goals faster. Your best self is waiting – let’s make it happen together!

FAQ:

The short answer is yes. However,  while BMR plays a role, it’s not a sustainable solution on its own. Remember that BMR only reflects the calories burned at rest, excluding those burned during activities like walking, talking, or exercising. When designing a meal plan customized to your caloric requirements, make sure to consider your present activity level or any planned increases due to exercise. This involves converting your BMR (Basal Metabolic Rate) into your  TDEE (Total Daily Energy Expenditure) to ensure accurate estimations.

A high Basal Metabolic Rate means that your body needs more calories to maintain basic bodily functions over a day. On the other hand, having a low BMR  means a slower metabolism. Ultimately, adopting a balanced lifestyle with regular exercise and nutritious dietary habits is important.

Your Basal Metabolic Rate (BMR) denotes the energy your body burns at rest, under conditions of physical and psychological calm, within a thermally neutral environment (such as room temperature), and during a postabsorptive state (i.e., not in the process of digestion). BMR is determined by factors including sex, weight, age, and height.

BMR Formula for Men:

88.362 + (13.397 x weight in kilograms) + (4.799 x height in centimeters) – (5.677 x age in years)

BMR Formula For Women: 

BMR = 447.593 + (9.247 x weight in kilograms) + (3.098 x height in centimeters) – (4.330 x age in years)

In general, men have a BMR ranging between 1,600 and 1,800 kilocalories per day, while women generally maintain a BMR of approximately 1,550 kilocalories per day. For those aged above 40, the average BMR tends to decrease to approximately 1,200 kilocalories per day.

Comana F. (n.d.). Resting metabolic rate: How to calculate and improve yours.
https://blog.nasm.org/nutrition/resting-metabolic-rate-how-to-calculate-and-improve-yours

Delsoglio M, et al. (2019). Indirect calorimetry in clinical practice.
https://pubmed.ncbi.nlm.nih.gov/31491883

Fernandes AC, et al. (2019). Perspective: Public health nutrition policies should focus on healthy eating, not on calorie counting, even to decrease obesity.
https://pubmed.ncbi.nlm.nih.gov/31305908/

Physical activity and controlling weight. (n.d.).
https://www.k-state.edu/paccats/Contents/PA/PDF/Physical%20Activity%20and%20Controlling%20Weight.pdf

Appendix 2. estimated calorie needs per day, by age, sex, and physical activity level. (2015).
https://health.gov/dietaryguidelines/2015/guidelines/appendix-2/

Merritt, A. (2019). BMR versus RMR.
https://www.acefitness.org/fitness-certifications/ace-answers/exam-preparation-blog/616/bmr-versus-rmr

Bendavid I, et al. (2021). The centenary of the Harris-Benedict equations: How to assess energy requirements best? Recommendations from the ESPEN expert group.
https://pubmed.ncbi.nlm.nih.gov/33279311/

Dahle JH, et al. (2021). Weight and body composition changes affect resting energy expenditure predictive equations during a 12-month weight-loss intervention. https://endocrinologia.org.mx/pdf_socios/121_Weight_body_composition_changes_Obesity_2021.pdf

Dent R, et al. (2020). Factors affecting weight loss variability in obesity.
https://pubmed.ncbi.nlm.nih.gov/33035570/

Pavlidou E, et al. (2018). Estimating the agreement between the metabolic rate calculated from prediction equations and from a portable indirect calorimetry device: An effort to develop a new equation for predicting resting metabolic rate.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6003108/

Stavres JR, et al. (2018). Six weeks of moderate functional resistance training increases basal metabolic rate in sedentary adult women.
https://digitalcommons.wku.edu/cgi/viewcontent.cgi?article=2051&context=ijes

Kelly, M. P. (n.d.). Resting metabolic rate: Best ways to measure it — and raise it, too. 
https://www.acefitness.org/certifiednewsarticle/2882/resting-metabolic-rate-best-ways-to-measure-it-and/

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What Can You Expect..

IIFYM Transformation -3

Laura Wand

32 y/o

IIFYM has been a game-changer for me! I've lost 20 lbs while enjoying my favorite treats. Thanks to this flexible approach, I've found a sustainable way to maintain my progress.

IIFYM Transformation -5

Sophia

41 y/o

IIFYM's Macro Blueprint transformed my diet. I've lost 15 pounds and feel amazing! It's the most personalized program I've ever tried.

IIFYM Transformation -4

Olivia

29 y/o

IIFYM made me realize that healthy eating doesn't have to be boring. It's been a delicious journey, and I've never felt better! 🥦🍔🍰