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BMR Calculator

Calculate Basal Metabolic Rate — the calories your body needs at rest — using Mifflin-St Jeor formula.

About This Calculator

BMR (Basal Metabolic Rate) is the number of calories your body needs to maintain basic physiological functions at complete rest — breathing, circulation, cell production, and organ function. This calculator uses the Mifflin-St Jeor equation, the most accurate formula recommended by dietitians and sports scientists.

How to Use This Calculator

  1. 1Select your biological gender
  2. 2Choose metric or imperial units
  3. 3Enter your age, weight, and height
  4. 4Select your typical activity level
  5. 5Click Calculate to see BMR and total daily calorie needs

Formula Used

Male BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5 | Female BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161

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FAQ

Frequently Asked Questions

Common questions about the bmr calculator answered.

What is the difference between BMR and TDEE?+
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just to keep you alive. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor to account for exercise and daily movement. TDEE is the number you actually use for weight management planning.
How do I use BMR to lose weight?+
To lose weight, eat fewer calories than your TDEE. A deficit of 500 calories per day leads to approximately 0.5 kg (1 lb) of fat loss per week. Never eat below your BMR as this can cause muscle loss and metabolic slowdown. A safe approach is eating at 80-90% of your TDEE.
Which BMR formula is most accurate?+
The Mifflin-St Jeor equation (used in this calculator) is considered the most accurate for most people. The Harris-Benedict equation is older and slightly less accurate. The Katch-McArdle formula requires body fat percentage but is most accurate for lean individuals. All formulas are estimates with 10-15% individual variation.
Does BMR decrease with age?+
Yes. BMR naturally decreases approximately 1-2% per decade after age 20 due to gradual loss of muscle mass. This is why many people notice weight gain with age even without changing their diet. Strength training to maintain muscle mass is the most effective way to preserve a higher BMR as you age.
How does muscle mass affect BMR?+
Muscle tissue is metabolically active and burns approximately 6 calories per pound per day at rest, compared to about 2 calories per pound for fat tissue. This is why two people with the same weight but different body compositions have different BMRs. Increasing muscle mass through resistance training raises your BMR.

BMR Calculator for Weight Management

Understanding your BMR is the foundation of any effective diet or fitness plan. Once you know your BMR and TDEE, you can set precise calorie targets. To lose 0.5 kg per week, create a 500-calorie daily deficit from your TDEE. To gain muscle, eat 200-300 calories above TDEE with a high-protein diet. To maintain weight, eat at your TDEE.

  • Weight loss: TDEE minus 300 to 500 calories daily
  • Muscle gain: TDEE plus 200 to 300 calories daily
  • Maintenance: Eat at your TDEE level
  • High protein intake (1.6-2.2g per kg) preserves muscle during deficit

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