BMR Calculator

Use this free BMR Calculator to estimate how many calories your body may burn at rest. Enter your age, sex, height and weight to calculate your estimated Basal Metabolic Rate and see how activity can change your total daily calorie needs.

What Is BMR?

BMR stands for Basal Metabolic Rate.

It is an estimate of the amount of energy your body uses while at rest to support basic life-sustaining functions.

Even when you are not exercising, your body still requires energy for processes such as:

• breathing
• circulation
• maintaining body temperature
• normal organ function
• cell activity

Your BMR is therefore the foundation of your daily calorie expenditure, but it is not the same as the total number of calories you burn in a normal day.

How Does the BMR Calculator Work?

Our calculator uses the Mifflin–St Jeor equation.

The formula uses:

• age
• sex
• height
• body weight

to estimate resting energy needs.

Mifflin–St Jeor Formula for Men

BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5

Mifflin–St Jeor Formula for Women

BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

The result is an estimate rather than a direct measurement of your metabolism.

BMR Example

Imagine a 30-year-old man who weighs 80 kg and is 180 cm tall.

The equation would be:

(10 × 80) + (6.25 × 180) − (5 × 30) + 5

That becomes:

800 + 1,125 − 150 + 5

Estimated BMR:

1,780 calories per day

This means his body may use roughly 1,780 calories per day at rest before daily movement and exercise are considered.

BMR vs TDEE

BMR and TDEE are closely related, but they are not the same.

BMR

BMR estimates your resting calorie expenditure.

TDEE

TDEE stands for Total Daily Energy Expenditure.

It attempts to estimate all the calories you use during a normal day after activity is included.

The basic relationship is:

TDEE = BMR × Activity Factor

For example, someone with a BMR of 1,700 calories and a moderate activity multiplier of 1.55 would have an estimated TDEE of:

1,700 × 1.55 = 2,635 calories per day

This is why your BMR should not automatically be treated as your daily calorie target.

For a dedicated estimate of your daily calorie expenditure, use our TDEE Calculator.

BMR vs Maintenance Calories

Maintenance calories are the estimated number of calories needed to keep your body weight relatively stable over time.

Your BMR does not include most normal daily activity.

Maintenance calories are therefore usually higher than BMR.

For example:

BMR: 1,600 calories

could become:

Maintenance calories: 2,200–2,500+ calories

depending on activity.

If you want to estimate how much you should actually eat each day, use our Calorie Calculator rather than eating directly according to your BMR.

Should You Eat Your BMR to Lose Weight?

Not automatically.

BMR represents your estimated resting energy expenditure.

In real life, most people do not spend the entire day completely at rest.

Walking, standing, working, exercising and normal daily movement all require additional energy.

This means eating exactly at BMR may create a larger calorie deficit than intended.

A better approach is usually to estimate your TDEE first and create a calorie deficit from your total daily energy expenditure.

What Affects Your BMR?

Several factors influence resting energy expenditure.

Body Size

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

Lean Body Mass

Muscle and other lean tissues contribute to resting energy expenditure.

People with more lean mass often have higher resting calorie needs.

Age

Resting energy expenditure can change with age, partly because body composition and other physiological factors may change over time.

Sex

Predictive equations use different constants for males and females because average body composition and energy expenditure patterns differ across populations.

Genetics and Individual Differences

Two people with similar body measurements can still have different measured energy expenditures.

This is one reason calculator results should always be viewed as estimates.

Does Muscle Increase BMR?

Lean body mass is an important contributor to resting energy expenditure.

People with more lean tissue often have higher resting calorie needs than people of the same body weight with less lean mass.

However, adding a small amount of muscle does not suddenly increase metabolism by hundreds of calories per day.

Muscle gain can contribute to resting energy expenditure, but total daily calorie burn is also heavily influenced by body size and activity.

Why Does BMR Decrease With Age?

Many people notice that estimated BMR decreases as they get older.

Age appears directly in common predictive equations, but age itself is not the only reason metabolism can change.

Changes in:

• muscle mass
• body weight
• physical activity
• hormone levels
• lifestyle

can also influence energy expenditure.

Maintaining muscle and staying physically active can therefore be useful for more than simply increasing exercise calorie burn.

What Is a Normal BMR?

There is no single “normal” BMR that everyone should have.

BMR varies according to:

• body size
• age
• sex
• body composition

A smaller person may naturally have a lower BMR than a taller or heavier person.

Comparing your BMR with someone else’s is usually less useful than understanding how your own estimate connects to your daily calorie needs.

Is a Higher BMR Better?

Not necessarily.

A higher BMR simply means your body is estimated to use more energy at rest.

It does not automatically mean that someone is healthier, fitter or has a “better metabolism.”

Body size and lean mass strongly influence resting energy requirements.

How Accurate Is a BMR Calculator?

A BMR calculator cannot directly measure your metabolism.

It uses a predictive equation.

The Mifflin–St Jeor equation is widely used to estimate resting energy expenditure, but individual results can still differ from measured values. Current BMR-focused tools also commonly use this equation as their default method.

The most accurate way to measure resting energy expenditure requires specialized testing such as indirect calorimetry.

For most people, however, a calculator provides a practical starting estimate.

BMR and Activity Levels

Once you know your BMR, you can estimate total daily energy expenditure by applying an activity multiplier.

Common activity factors include:

Sedentary: 1.20

Lightly Active: 1.375

Moderately Active: 1.55

Very Active: 1.725

Extra Active: 1.90

Our calculator shows estimated daily calorie expenditure at each activity level so you can see how much movement can change the final number.

Why Your Activity Multiplier Is Only an Estimate

Activity multipliers are broad categories.

Two people who both choose “moderately active” may still have different daily energy expenditures.

One person may:

• walk 12,000 steps
• train for an hour
• have an active job

while another may:

• work at a desk
• train for one hour
• move very little outside the gym

Both could describe themselves as moderately active, but their real energy expenditure may differ.

Use activity multipliers as starting assumptions, not precise measurements.

BMR Calculator vs Calorie Calculator

A BMR Calculator focuses on your estimated energy use at rest.

A Calorie Calculator goes further by applying activity and converting that estimate into calorie targets for:

• weight loss
• maintenance
• weight gain

If your goal is simply understanding your resting metabolism, use the BMR Calculator.

If your goal is deciding how much to eat, use our Calorie Calculator.

BMR Calculator vs Macro Calculator

A BMR Calculator only estimates resting calorie expenditure.

A Macro Calculator estimates daily calories and then divides those calories between:

• protein
• carbohydrates
• fat

This makes the Macro Calculator more useful when you are planning an actual nutrition target.

What Should You Calculate Next?

Once you know your BMR, the next step is understanding your complete daily energy expenditure.

Use our TDEE Calculator to estimate how many calories you may burn during an average day.

Use our Calorie Calculator to calculate starting calorie targets for fat loss, maintenance or weight gain.

Use our Macro Calculator to divide your daily calories into protein, carbohydrates and fat.

If you mainly want to know how much protein you need, try our Protein Calculator.

Frequently Asked Questions

What does BMR stand for?

BMR stands for Basal Metabolic Rate. It estimates how many calories your body uses while at rest to maintain basic body functions.

How do I calculate my BMR?

Our calculator uses the Mifflin–St Jeor equation based on age, sex, height and weight.

Is BMR the same as metabolism?

BMR is one part of metabolism. It represents resting energy expenditure, while your total daily calorie burn also includes movement, exercise and other energy costs.

Is BMR the same as TDEE?

No. BMR estimates resting calorie expenditure, while TDEE includes activity and represents a broader estimate of total daily calorie use.

Should I eat fewer calories than my BMR to lose weight?

You generally should not create your calorie target by simply subtracting calories from BMR. Estimate your TDEE and build your calorie deficit from total daily energy expenditure instead.

Why is my BMR lower than my maintenance calories?

BMR only estimates calories used at rest. Maintenance calories include everyday activity, which increases total energy expenditure.

Does exercise increase BMR?

Exercise itself raises daily energy expenditure. Resistance training may also help build or maintain lean mass, which contributes to resting energy needs.

Can two people have the same BMR?

Yes. Different combinations of age, body size and sex can sometimes produce similar estimated BMR values.

Should I use BMR or TDEE for weight loss?

TDEE is generally the more useful starting point for setting weight-loss calories because it includes activity.

How often should I recalculate my BMR?

Recalculate after meaningful changes in body weight or body size. Small day-to-day weight changes do not require a new calculation.

Disclaimer

The BMR Calculator and information on this page are provided for general educational and fitness-planning purposes only.

Results are estimates and are not medical advice, diagnosis or a personalized nutrition prescription.

Individual resting energy expenditure can differ from predictive equations. People with medical conditions, pregnancy, special dietary requirements or other health concerns should seek advice from an appropriately qualified healthcare professional.