BMR Calculator
Calculate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE). Find out how many calories your body burns at rest and with activity.
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Your BMR Results
Our BMR Calculator is an efficient and easy-to-use instrument that is created to assist you in understanding the energy consumption of your body. In any case, if you are outlining a weight loss trip, intending to gain muscle, or just being curious about your metabolism, this calculator gives you the precise figures that are derived from the Mifflin-St Jeor equation which has been scientifically validated. To assess your body composition and health risks, pair this with our BMI calculator for a complete health profile.
The calculator figures out your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) by factoring in your age, gender, height, weight, and activity level. It's up to you to decide whether to use metric or imperial units as the calculator is compatible with both. Your data can be keyed in the way that suits you best.
Not only numbers, our tool gives full insights which include detailed step-by-step calculation breakdowns, individualized weight management suggestions, and graphics showing your calorie usage throughout the day. With this, it becomes a lot easier to take the right nutrition and fitness decisions as per your goals.
What is BMR?
Basal Metabolic Rate (BMR) refers to the minimum calorie intake that the body needs to carry out the most basic physiological functions when it is in total rest. A good way to understand it is as the energy that the body demands to keep the vital functions going - which is the case if you were to lie in bed all day without making any movements at all.
Your BMR makes up around 60-75% of your total daily calorie expenditure, thus, it is the biggest factor of your energy requirements. This metabolic baseline is what energizes the essential bodily processes that are happening non-stop, among others:
- Respiratory functions: The energy needed for breathing and oxygenating your blood
- Circulatory processes: Maintaining blood flow and heart function
- Cellular activities: Cell production, repair, and regeneration throughout your body
- Neurological operations: Brain function and nerve signal transmission
- Thermoregulation: Maintaining your core body temperature at approximately 98.6°F (37°C)
- Digestive processes: Basic nutrient processing and metabolic reactions
- Organ function: The continuous work performed by your liver, kidneys, and other vital organs
It is very important to know your BMR as it is the very minimum amount of calories that you should consume in a day. If you eat less than your BMR for several days or weeks, your body will go into a state where your metabolism will slow down as an adaptation to the situation, thus causing weight loss to become more difficult and your health can also be at risk.
How to Calculate Your BMR
Figuring out your BMR means you have to use a formula that takes into account the bare minimum features of a human body. The best and the most popular way to do it is the Mifflin-St Jeor equation, which has been confirmed by several research studies and is considered to be better than the ones like the Harris-Benedict that are obsolete.
Step 1: Gather Your Information
Before you begin, you'll need to know:
- Your current weight in kilograms (or convert from pounds by dividing by 2.2046)
- Your height in centimeters (or convert from inches by multiplying by 2.54)
- Your age in years
- Your biological sex (male or female)
Step 2: Apply the Mifflin-St Jeor Formula
The formula differs slightly for men and women due to differences in body composition and metabolic rates:
For Men:
BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(years) + 5
For Women:
BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(years) - 161
Step 3: Break Down the Calculation
The formula works by:
- Weight component (10 × weight): Accounts for the energy needed to maintain your body mass
- Height component (6.25 × height): Reflects the metabolic cost of your body surface area
- Age component (-5 × age): Adjusts for the natural decline in metabolism as you age
- Gender constant (+5 for men, -161 for women): Compensates for differences in muscle mass and body composition between genders
Step 4: Calculate TDEE (Optional but Recommended)
Once you have your BMR, multiply it by an activity factor to get your Total Daily Energy Expenditure (TDEE), which represents your actual daily calorie needs:
Our calculator automates all these steps for you, providing instant results along with detailed explanations of each calculation phase.
Example BMR Calculation
Let's walk through a real-world example to see how BMR is calculated in practice. This will help you understand exactly how the numbers work together.
Example Scenario:
- Gender: Female
- Age: 35 years
- Weight: 68 kg (150 lbs)
- Height: 165 cm (5'5")
Step-by-Step Calculation:
Using the Mifflin-St Jeor equation for women:
BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(years) - 161
Substituting the values:
BMR = 10 × 68 + 6.25 × 165 - 5 × 35 - 161
BMR = 680 + 1,031.25 - 175 - 161
BMR = 680 + 1,031.25 = 1,711.25
BMR = 1,711.25 - 175 = 1,536.25
BMR = 1,536.25 - 161 = 1,375 calories/day
Interpreting the Result:
Our example individual thus consumes around 1,375 calories each day only to keep her body functioning at total rest. In case she leads a sedentary life (almost no physical activity), her TDEE will be:
For instance, if she is targeting weight loss, her daily calorie intake can be between 1,150-1,200 (which is a 450-500 calorie deficit) and she has to make sure that her body doesn't get less than her BMR of 1,375 calories. The case hereby is an argument of how pivotal knowing one's BMR is in the accomplishment of weight management that is both safe and efficient.
What is the Difference Between BMR and RMR?
While BMR (Basal Metabolic Rate) and RMR (Resting Metabolic Rate) are often used interchangeably, they represent slightly different measurements that can impact your calorie calculations and fitness planning.
Basal Metabolic Rate (BMR):
BMR is measured under very strict, controlled conditions that represent the absolute minimum energy expenditure. To get an accurate BMR reading, you would need to:
- Fast for at least 12 hours (no food or beverages)
- Rest in a temperature-controlled environment
- Avoid any physical activity for 24 hours prior
- Measure immediately upon waking, while still lying down
- Be in a completely relaxed, post-absorptive state
Resting Metabolic Rate (RMR):
RMR is measured under less stringent conditions and is typically slightly higher than BMR. RMR measurements allow for:
- Normal daily activities before measurement
- Recent food consumption (within a few hours)
- Less controlled environmental conditions
- Measurement at any time of day after a period of rest
Key Differences:
- Measurement conditions: BMR requires strict fasting and rest, while RMR is more flexible
- Typical values: RMR is usually 10-20% higher than BMR due to recent food intake and activity
- Practical use: RMR is easier to measure in real-world settings, while BMR provides the most accurate baseline
- Clinical applications: BMR is preferred for research and medical purposes, while RMR is commonly used in fitness settings
Which Should You Use?
Basically, BMR and RMR are almost the same (around 100-300 calories) for most practical uses such as weight management and fitness planning. The computation in our calculator is based on the BMR formula which gives a lower value to be sure that you still have the absolute minimum your body requires. This method is less risky for weight loss plans as it stops you from unintentionally making too big of a calorie deficit.
In case you are collaborating with a fitness expert or have the privilege to use some metabolic testing tools, RMR measurements may be able to give you results that are a bit more tailored to your body. Nevertheless, when it comes to home use and general fitness planning, BMR estimations with the Mifflin-St Jeor equation (the method that this calculator follows) are quite precise and are considered valid by most of the scientific community.
Understanding TDEE
TDEE is your total daily calorie burn, calculated as:
Activity multipliers:
- Sedentary (×1.2): Little or no exercise, desk job
- Light (×1.375): Light exercise 1-3 days/week
- Moderate (×1.55): Moderate exercise 3-5 days/week
- Active (×1.725): Hard exercise 6-7 days/week
- Very Active (×1.9): Very hard exercise, physical job, or training twice daily
Using BMR for Weight Management
How to use your BMR and TDEE:
- Weight Loss: Create a calorie deficit of 500-1000 calories per day below your TDEE for safe, sustainable weight loss (1-2 lbs/week)
- Weight Maintenance: Eat calories equal to your TDEE
- Weight Gain: Create a calorie surplus of 250-500 calories per day above your TDEE for gradual weight gain (0.5-1 lb/week)
- Important: Never consume fewer calories than your BMR, as this can slow metabolism and be counterproductive
Factors Affecting BMR
Several factors influence your BMR:
- Age: BMR decreases with age due to loss of muscle mass
- Gender: Men typically have higher BMR due to more muscle mass
- Body Composition: Muscle burns more calories than fat at rest
- Genetics: Some people naturally have faster or slower metabolisms
- Hormones: Thyroid function and other hormones affect metabolism
- Diet: Severe calorie restriction can lower BMR
Tip: BMR calculators only give rough figures. If you really want to know your exact BMR, go for a professional metabolic test. Work with your BMR figure that you got from the calculation and make your own judgement. In case you don't get the results that you were expecting after 2-3 weeks, change your calorie consumption.
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