BMR Calculator - Calculate Your Basal Metabolic Rate

BMR Calculator

Calculate Your Basal Metabolic Rate

Calculate Your BMR

Your Metabolic Results

Basal Metabolic Rate (BMR):

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Calories needed per day at complete rest

Total Daily Energy Expenditure (TDEE):

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Calories needed per day based on your activity level

Weight Management Guidelines

Mild weight loss (0.25 kg/week):

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Calories per day (TDEE - 250 kcal)

Weight loss (0.5 kg/week):

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Calories per day (TDEE - 500 kcal)

Extreme weight loss (1 kg/week):

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Calories per day (TDEE - 1000 kcal)

Weight gain (0.5 kg/week):

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Calories per day (TDEE + 500 kcal)

About Basal Metabolic Rate (BMR)

Your Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic physiological functions at complete rest, including breathing, circulation, and cell production. Understanding your BMR is essential for:

  • Effective weight management - Set accurate calorie targets for weight loss or gain
  • Personalized nutrition planning - Create meal plans tailored to your metabolic needs
  • Health monitoring - Track metabolic changes due to aging or lifestyle factors

Real-World Examples

Example 1: Weight Loss

Profile: 35-year-old male, 80kg, 178cm, moderately active

Calculation (Mifflin-St Jeor):

BMR = (10 × 80) + (6.25 × 178) - (5 × 35) + 5 = 1,735 kcal/day

TDEE (Moderate Activity): 1,735 × 1.55 = 2,689 kcal/day

Weight Loss Target (0.5kg/week): 2,689 - 500 = 2,189 kcal/day

Example 2: Muscle Gain

Profile: 25-year-old female, 60kg, 165cm, very active

Calculation (Harris-Benedict):

BMR = 447.6 + (9.25 × 60) + (3.1 × 165) - (4.33 × 25) = 1,387 kcal/day

TDEE (Very Active): 1,387 × 1.725 = 2,393 kcal/day

Muscle Gain Target: 2,393 + 300 = 2,693 kcal/day

Formulas Used

1. Mifflin-St Jeor Equation (Most Accurate)

For Men:

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

For Women:

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

2. Revised Harris-Benedict Formula

For Men:

BMR = 88.362 + (13.397 × weight) + (4.799 × height) - (5.677 × age)

For Women:

BMR = 447.593 + (9.247 × weight) + (3.098 × height) - (4.330 × age)

3. Katch-McArdle Formula (Requires Body Fat %)

Lean Mass = Weight × (100 - Body Fat %) / 100

BMR = 370 + (21.6 × Lean Mass in kg)

Activity Level Multipliers

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

Privacy & Security

We take your privacy seriously:

  • All calculations are performed in your browser - no data is sent to any server
  • We do not store any of your personal information
  • No cookies or tracking technologies are used
  • Your health data never leaves your device

Frequently Asked Questions

Why does my BMR decrease with age?

After age 20, metabolism typically slows by about 2% per decade due to natural muscle loss and hormonal changes. This is why maintaining muscle mass through strength training becomes increasingly important as you age.

How accurate are BMR calculators?

Online BMR calculators provide estimates that are typically within 5-10% of your actual metabolic rate. For clinical precision, medical professionals use indirect calorimetry to measure oxygen consumption and carbon dioxide production.

Can I increase my BMR?

Yes! Building muscle through strength training is the most effective way to boost your BMR. Other factors include proper hydration, adequate protein intake, and maintaining an active lifestyle.

Why do men typically have higher BMR than women?

Men generally have more muscle mass and less body fat than women of similar size and age. Since muscle tissue burns more calories at rest than fat tissue, this results in a higher BMR.

How often should I recalculate my BMR?

You should recalculate whenever your weight changes significantly (±5kg), or every 3-6 months to account for natural metabolic changes. Also recalculate if your activity level changes substantially.

Important Notes

This calculator provides estimates only. Individual metabolic rates can vary based on genetics, medical conditions, and other factors. For personalized medical advice, please consult with a healthcare professional or registered dietitian.

Extreme calorie restriction (below BMR) can be harmful and may actually slow your metabolism over time. For sustainable weight loss, most experts recommend a modest deficit of 300-500 calories below your TDEE.