BMR Calculator

Category: Fitness
- April 04, 2025
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Calculate your Basal Metabolic Rate (BMR) - the number of calories your body needs at rest to maintain basic functions.

Personal Information

Calculation Method

Activity Level

Goal

Display Options

About Basal Metabolic Rate (BMR)

Basal Metabolic Rate (BMR) is the number of calories your body needs while resting, to maintain basic functions such as breathing, circulation, and cell production.

BMR Calculation Methods
  • Mifflin-St Jeor Equation: Considered the most accurate formula for estimating BMR.
    • For men: BMR = 10W + 6.25H - 5A + 5
    • For women: BMR = 10W + 6.25H - 5A - 161
    Where W is weight in kg, H is height in cm, and A is age in years.
  • Harris-Benedict Equation: An older but still widely used formula.
    • For men: BMR = 13.397W + 4.799H - 5.677A + 88.362
    • For women: BMR = 9.247W + 3.098H - 4.330A + 447.593
  • Katch-McArdle Formula: Takes into account lean body mass, which can be more accurate for those who know their body fat percentage.
    • BMR = 370 + (21.6 × LBM)
    • Where LBM is lean body mass in kg = Weight - (Weight × Body Fat %)
Total Daily Energy Expenditure (TDEE)

TDEE is your BMR multiplied by an activity factor:

  • Sedentary (little or no exercise): BMR × 1.2
  • Lightly active (light exercise 1-3 days/week): BMR × 1.375
  • Moderately active (moderate exercise 3-5 days/week): BMR × 1.55
  • Very active (hard exercise 6-7 days/week): BMR × 1.725
  • Extra active (very hard exercise & physical job): BMR × 1.9
Using BMR for Weight Management

Understanding your BMR and TDEE can help you manage your weight:

  • Weight Maintenance: Consume your TDEE calories
  • Weight Loss: Consume fewer calories than your TDEE
  • Weight Gain: Consume more calories than your TDEE

A calorie deficit of approximately 3,500 calories is equivalent to losing about 1 pound (0.45 kg) of body fat.

Factors Affecting BMR
  • Age: BMR decreases with age
  • Gender: Men generally have a higher BMR than women
  • Body Composition: Higher muscle mass increases BMR
  • Genetics: Family history can affect your metabolic rate
  • Hormones: Thyroid issues and other hormonal conditions can affect BMR
  • Health Status: Various illnesses can impact BMR
  • Climate: Living in extreme climates may increase BMR

What is a BMR Calculator?

The BMR Calculator helps you estimate the number of calories your body needs each day to carry out essential functions while at rest. This is what we call your Basal Metabolic Rate (BMR). It gives you a clearer idea of how many calories your body uses just to keep you alive—like breathing, circulation, and maintaining body temperature.

Once you know your BMR, you can use it to work out your Total Daily Energy Expenditure (TDEE), which includes calories burned through activities. This is useful for planning your daily calorie intake whether your goal is to lose, gain, or maintain weight.

Common BMR Formulas

Mifflin-St Jeor Equation
Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
Harris-Benedict Equation
Men: BMR = 13.397 × weight(kg) + 4.799 × height(cm) − 5.677 × age + 88.362
Women: BMR = 9.247 × weight(kg) + 3.098 × height(cm) − 4.330 × age + 447.593
Katch-McArdle Formula
BMR = 370 + (21.6 × Lean Body Mass in kg)
Lean Body Mass = Weight − (Weight × Body Fat %)

How to Use the Calculator

Using the BMR Calculator is straightforward. Just follow these steps to get your results:

  • Select your gender.
  • Enter your age, weight, and height. You can choose between metric (kg/cm) and imperial (lbs/in) units.
  • Choose a formula:
    • Mifflin-St Jeor: Recommended for general use.
    • Harris-Benedict: An alternative formula, slightly older.
    • Katch-McArdle: Best if you know your body fat percentage.
  • Select your activity level. This adjusts your BMR to calculate your TDEE (Total Daily Energy Expenditure).
  • Choose your goal: Maintain, lose, or gain weight.
  • Click "Calculate BMR". Your results will show up below.

What the Results Mean

  • BMR: The calories your body burns while at rest.
  • TDEE: Your daily calorie needs based on your activity level.
  • Calories for Goal: A recommended daily intake based on your selected goal (e.g., weight loss or gain).

If enabled, you’ll also see a suggested breakdown of macronutrients (protein, carbohydrates, and fat) based on standard nutritional guidelines.

Why BMR Matters

Knowing your BMR and TDEE is helpful for setting realistic calorie targets. It helps you:

  • Lose weight: By creating a calorie deficit (eating fewer calories than you burn).
  • Gain weight: By consuming more calories than your body uses.
  • Maintain weight: By aligning your intake with your daily energy needs.

This approach can support your fitness goals, improve energy management, and contribute to better long-term health.

Frequently Asked Questions (FAQ)

  • Is the Mifflin-St Jeor formula the best?
    Yes, it’s generally considered the most accurate for general use unless you know your exact body fat percentage.
  • What’s the difference between BMR and TDEE?
    BMR is your body's calorie requirement at rest. TDEE includes your daily physical activity and is usually higher.
  • Can I use this to plan my diet?
    Definitely. By knowing your calorie needs, you can make better choices about portion sizes, meal frequency, and nutritional balance.
  • Do I need to enter my body fat percentage?
    Only if you choose the Katch-McArdle formula, which uses that info for a more accurate estimate.
  • Is this tool for athletes only?
    No. It’s suitable for anyone who wants to understand their calorie needs—whether you're active, sedentary, or somewhere in between.

Key Benefits

  • Quickly estimate daily calorie needs.
  • Choose from different calculation methods.
  • Adjust for activity and fitness goals.
  • See macronutrient recommendations (if enabled).
  • Supports informed eating and weight planning.

This calculator is a handy starting point for setting and tracking your fitness or nutrition goals with more confidence and clarity.