How to Calculate BMR: Formula, Examples for Men and Women

If you want to know how to calculate BMR, you can estimate your Basal Metabolic Rate using your age, sex, height, and weight. BMR represents the amount of energy your body needs to support essential functions such as breathing, circulation, and maintaining normal body processes while at rest.

The easiest approach for most adults is the Mifflin-St Jeor equation. You can also use the CalcMax BMR Calculator to calculate your estimated BMR automatically.

What Is BMR?

BMR stands for Basal Metabolic Rate. It is an estimate of the energy your body requires to maintain basic physiological functions when you are at rest.

Your body continues using energy even when you are sleeping or sitting still. This energy supports functions such as:

• Breathing

• Heart function

• Blood circulation

• Maintaining body temperature

• Cell and tissue maintenance

• Basic organ function

BMR is therefore different from the number of calories you burn through exercise or everyday movement.

For example, someone with a BMR of 1,600 calories does not necessarily need to eat exactly 1,600 calories per day. Their total daily energy expenditure will usually be higher because it also includes physical activity, digestion, and other daily movements.

How to Calculate BMR

The Mifflin-St Jeor equation is one of the commonly used formulas for estimating resting energy expenditure. It was developed from research involving healthy adult men and women.

For the calculation, you need:

• Weight in kilograms

• Height in centimetres

• Age in years

• Sex

BMR Formula for Men

The Mifflin-St Jeor equation for men is:

BMR = (9.99 × weight in kg) + (6.25 × height in cm) − (4.92 × age) + 5

BMR Formula for Women

For women:

BMR = (9.99 × weight in kg) + (6.25 × height in cm) − (4.92 × age) − 161

These formulas are also presented in the National Center for Biotechnology Information's Endotext reference on estimating resting metabolic rate.

How to Calculate BMR in Female

If you're searching for how to calculate BMR in female, use the female version of the Mifflin-St Jeor equation:

BMR = (9.99 × weight) + (6.25 × height) − (4.92 × age) − 161

Use weight in kilograms and height in centimetres.

Example: Female BMR Calculation

Suppose a woman is:

• Age: 30

• Weight: 65 kg

• Height: 165 cm

The calculation is:

BMR = (9.99 × 65) + (6.25 × 165) − (4.92 × 30) − 161

BMR ≈ 1,372 calories per day

This means her estimated resting energy requirement is approximately 1,372 calories per day according to this equation.

It does not mean that 1,372 calories is automatically her recommended daily calorie intake. Her actual daily energy needs depend on activity and other factors.

For a quicker calculation, use the BMR Calculator and enter your personal information.

How to Calculate BMR in Male

If you're looking for how to calculate BMR in male, use:

BMR = (9.99 × weight) + (6.25 × height) − (4.92 × age) + 5

Again, weight should be entered in kilograms and height in centimetres.

Example: Male BMR Calculation

Suppose a man is:

• Age: 30

• Weight: 80 kg

• Height: 180 cm

The calculation is:

BMR = (9.99 × 80) + (6.25 × 180) − (4.92 × 30) + 5

BMR ≈ 1,782 calories per day

This is an estimated resting energy expenditure, not a personalized calorie prescription.

What Does Your BMR Number Mean?

Your BMR gives you an estimate of how much energy your body uses for basic functions at rest.

For example:

Estimated BMRWhat it represents1,300 kcal/dayEstimated resting energy requirement1,500 kcal/dayEstimated resting energy requirement1,800 kcal/dayEstimated resting energy requirement2,000 kcal/dayEstimated resting energy requirement

A higher or lower BMR isn't automatically "good" or "bad." BMR varies between people because factors such as body size, age, sex, and body composition influence energy expenditure.

BMR vs TDEE: What's the Difference?

One of the most important things to understand is the difference between BMR and TDEE.

BMR estimates the energy required for basic body functions at rest.

TDEE, or Total Daily Energy Expenditure, estimates the total amount of energy you use throughout an average day.

TDEE can include:

• Resting metabolic needs

• Walking and everyday movement

• Exercise

• Work-related physical activity

• Energy used during digestion

A simplified way to think about it is:

BMR → basic energy needs

TDEE → BMR + activity + other daily energy expenditure

This is why using your BMR alone to determine how many calories you should eat can be misleading.

How to Use BMR for Weight Loss

BMR can be a useful starting point when you're trying to understand your calorie requirements.

However, weight management should not be based on BMR alone. You first need to consider your overall daily energy expenditure.

For example:

BMR → estimate resting needs

Activity level → account for movement and exercise

TDEE → estimate total daily energy expenditure

Your calorie intake can then be considered in relation to your overall energy needs.

If your goal is weight loss, avoid assuming that eating as little as your calculated BMR is automatically appropriate. Individual calorie requirements vary, and aggressive calorie restriction may not be suitable for everyone.

For more health-related calculation tools, explore the CalcMax Health Calculators.

What Factors Affect BMR?

BMR isn't identical for everyone. Several factors can influence resting energy expenditure.

Age

Energy expenditure can change as you get older. Changes in body composition and other physiological factors can affect resting metabolic rate.

Body Size

Larger bodies generally require more energy to maintain basic functions than smaller bodies.

Height and Weight

Both are included in the Mifflin-St Jeor equation because they help estimate energy requirements.

Sex

The standard Mifflin-St Jeor equations use different constants for men and women.

Body Composition

Muscle and fat tissue have different metabolic characteristics. Because prediction equations use basic measurements rather than a detailed measurement of body composition, their results are estimates.

Health and Physiological Conditions

Illness, hormonal changes, medications, and other physiological factors can influence energy expenditure. A standard online equation cannot account for every individual factor.

Is the Mifflin-St Jeor Equation Accurate?

The Mifflin-St Jeor equation is useful, but it is not a direct measurement of your metabolism.

Research comparing prediction equations with measured resting metabolic rate has found that Mifflin-St Jeor performs well among commonly used equations, but individual errors still occur.

This distinction is important.

An online BMR calculator gives you an estimate based on a mathematical formula. It does not measure your metabolism directly.

For a direct measurement, specialized methods such as indirect calorimetry can be used in appropriate clinical or research settings.

BMR vs RMR: Are They the Same?

You may see the terms BMR and RMR (Resting Metabolic Rate) used interchangeably online, but they are not technically identical.

BMR refers to energy expenditure under highly controlled basal conditions. RMR generally refers to resting energy expenditure measured under less restrictive conditions.

The Mifflin-St Jeor equation is technically an equation for estimating resting energy expenditure, although many consumer calculators and websites label the result as BMR.

For everyday calorie-estimation purposes, the distinction is often less important than understanding that the result is an estimate of resting energy needs.

How to Calculate BMR Without Doing the Math

If you don't want to manually apply the formula, you can use the online BMR Calculator.

Simply enter your:

1. Age

2. Sex

3. Height

4. Weight

The calculator can then provide an estimated BMR without requiring you to work through the equation yourself.

You can also explore other health calculators to help with related calculations.

Common BMR Calculation Mistakes

When calculating BMR manually, watch for these common mistakes:

Using Pounds Instead of Kilograms

The Mifflin-St Jeor equation requires weight in kilograms.

If your weight is in pounds, convert it before using the formula.

1 kilogram ≈ 2.205 pounds

Using Feet Instead of Centimetres

The equation requires height in centimetres, not feet and inches.

For example:

5 ft 6 in ≈ 168 cm

Forgetting the Sex-Specific Constant

The final part of the equation differs:

• Men: +5

• Women: −161

Treating BMR as Your Daily Calorie Requirement

BMR represents resting energy expenditure. Your actual daily energy expenditure is generally higher because you move, exercise, work, and digest food.

BMR Calculation for Different Goals

Your BMR can be useful in different situations, but its role depends on your goal.

For Weight Loss

Use BMR as one input when estimating your overall energy requirements. TDEE is more useful for understanding total daily calorie expenditure.

For Weight Maintenance

Your estimated BMR can help provide a baseline, while your activity level helps estimate total calorie requirements.

For Muscle Gain

BMR can help establish a starting point for energy calculations, but nutrition planning should also consider training, protein intake, recovery, and overall calorie needs.

For Fitness Tracking

Tracking changes in weight, activity, and estimated energy needs over time can provide useful context, although calculator results should not be treated as exact measurements.

Frequently Asked Questions About How to Calculate BMR

How do you calculate BMR?

You can calculate BMR using your age, weight, height, and sex with an equation such as Mifflin-St Jeor. The result estimates your resting energy expenditure. For a faster calculation, use a BMR Calculator.

How to calculate BMR in female?

To calculate BMR in female adults using Mifflin-St Jeor, use: (9.99 × weight in kg) + (6.25 × height in cm) − (4.92 × age) − 161. The result is an estimate rather than a direct measurement.

How to calculate BMR in male?

To calculate BMR in male adults using Mifflin-St Jeor, use: (9.99 × weight in kg) + (6.25 × height in cm) − (4.92 × age) + 5. Enter your weight in kilograms and height in centimetres.

Is BMR the same as daily calorie needs?

No. BMR represents estimated energy requirements at rest. Your total daily calorie needs are usually higher because they include physical activity, exercise, digestion, and other energy expenditure.

Can a BMR calculator tell me how many calories I should eat?

A BMR calculator can provide a useful starting estimate, but BMR alone does not determine your appropriate calorie intake. Your activity level, body composition, goals, health status, and other factors also matter.

Conclusion

Learning how to calculate BMR gives you a useful starting point for understanding your body's energy requirements. The Mifflin-St Jeor equation uses age, weight, height, and sex to estimate resting energy expenditure, with different constants for men and women.

Remember that BMR is not the same as your total daily calorie requirement. For weight management, fitness, or nutrition planning, your activity level and overall energy expenditure also need to be considered.

For a quick and convenient calculation, use the CalcMax BMR Calculator to estimate your BMR without doing the formula manually.