BMR Calculator

Calculate your Basal Metabolic Rate (BMR) — the number of calories your body burns per day at complete rest.


What Is BMR (Basal Metabolic Rate)?

Basal Metabolic Rate (BMR) is the number of calories your body needs each day to perform its most essential functions while completely at rest. These functions include breathing, blood circulation, temperature regulation, organ function, and cell repair.

In simple terms, BMR represents the minimum amount of energy required to stay alive if you were resting for 24 hours with no physical activity.

Why BMR Is Important for Health and Fitness

Understanding your BMR is crucial because it forms the foundation for all calorie-based decisions. Every calorie calculation — including weight loss, muscle gain, or weight maintenance — starts with BMR.

Without knowing your BMR, it is easy to under-eat or over-eat, which can slow progress or negatively affect health.

How to Use the BMR Calculator

  1. Select your preferred unit system: Metric or Imperial.
  2. Choose your gender.
  3. Enter your age, height, and weight.
  4. Click the Calculate button.
  5. Review your BMR result in calories per day.

Your result shows how many calories your body burns at rest, before considering daily movement or exercise.

How Is BMR Calculated?

This calculator uses the scientifically validated Mifflin–St Jeor Equation, which is widely considered one of the most accurate methods for estimating basal metabolic rate in adults.

BMR Formula Used

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

When imperial units are selected, the calculator automatically converts pounds and inches into kilograms and centimeters for accuracy.

What Does Your BMR Result Mean?

Your BMR represents your body's baseline calorie requirement. Consuming fewer calories than your BMR for long periods may interfere with essential bodily functions.

  • Higher BMR: Your body burns more calories at rest.
  • Lower BMR: Your body burns fewer calories at rest.

BMR does not include calories burned from movement, exercise, or daily activities.

BMR vs Maintenance Calories vs TDEE

These three terms are closely related but serve different purposes:

  • BMR: Calories burned at complete rest.
  • Maintenance Calories: Calories needed to maintain weight.
  • TDEE: Total calories burned per day including activity.

Your maintenance calories and TDEE are essentially the same value, while BMR is the foundation used to calculate them.

To maintain weight, you should eat near your TDEE — not your BMR.

Factors That Affect BMR

Several biological and lifestyle factors influence basal metabolic rate:

  • Age: BMR typically declines with age.
  • Gender: Men often have higher BMR due to muscle mass.
  • Body Composition: Muscle burns more calories than fat.
  • Height & Weight: Larger bodies require more energy.
  • Genetics: Metabolism varies between individuals.

Can You Increase Your BMR?

While genetics influence metabolism, certain habits can support a higher BMR:

  • Building lean muscle through resistance training
  • Maintaining regular physical activity
  • Eating enough protein
  • Avoiding extreme calorie restriction

Healthy metabolism improvements occur gradually through consistent lifestyle habits.

Limitations of BMR Calculations

BMR calculators provide estimates, not exact measurements:

  • They cannot measure hormonal or metabolic disorders.
  • They do not account for daily movement.
  • Actual energy needs may differ slightly.

Use BMR as a guideline rather than a strict rule.

What to Do After Calculating Your BMR

Once you know your BMR, the next step is to calculate how many calories you need based on activity level.

Frequently Asked Questions (FAQs)

Is BMR the same for everyone?

No. BMR varies due to age, gender, body size, muscle mass, and genetics.

Should I eat below my BMR?

Consistently eating below BMR is generally not recommended, as it may negatively impact health and metabolism.

How often should I calculate my BMR?

Recalculate whenever your weight, age, or body composition changes significantly.

Is this BMR calculator accurate?

This calculator uses a scientifically validated formula that provides reliable estimates for most adults.

Final Thoughts

The BMR Calculator is a foundational tool for understanding your body's energy needs. When used correctly, it helps prevent extreme dieting and supports sustainable fitness planning.

For best results, combine BMR insights with activity-based calculators to build a complete nutrition strategy.