BMR Calculator - Basal Metabolic Rate

CENTER_DOCK
PRODUCTIVITY HUB

Calculation Formula

Personal Data

What Is Basal Metabolic Rate (BMR)?

Your Basal Metabolic Rate (BMR) represents the number of calories your body burns while at complete rest. Think of it as the energy cost of keeping your body running—breathing, circulating blood, controlling body temperature, producing hormones, and enabling cell growth and repair—without any physical activity. Even in a comatose state, your body would still burn these calories.

Which Formula Should You Use?

This calculator offers three major scientifically validated formulas:

  • Mifflin-St Jeor (Recommended): Considered the most accurate for modern lifestyles. It's the default recommendation by the American Dietetic Association and Academy of Nutrition and Dietetics. Best for the general population.
  • Harris-Benedict (Revised): One of the oldest formulas, originally published in 1919 and revised in 1984. It tends to slightly overestimate needs for modern, more sedentary populations but remains widely used.
  • Katch-McArdle: The only formula that accounts for Body Fat Percentage. It calculates based on lean body mass, making it the most accurate for lean athletes and those who know their body composition.

The Formulas Explained

Mifflin-St Jeor:

Men: (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5

Women: (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161

BMR vs. TDEE: What's the Difference?

It's important not to confuse BMR with TDEE:

  • BMR (Basal Metabolic Rate): Calories burned at complete rest (as if in a coma). This is your absolute minimum energy requirement.
  • TDEE (Total Daily Energy Expenditure): BMR + Calories burned from daily activities, exercise, and the thermic effect of food. Calculate this with our Calorie Calculator.

You should generally eat ABOVE your BMR but BELOW your TDEE to lose weight safely. Eating below BMR long-term can trigger metabolic adaptation.

What Factors Affect Your BMR?

  • Muscle Mass: Muscle tissue is more metabolically active than fat tissue. More muscle = higher BMR.
  • Age: BMR decreases by about 2% per decade after age 20, primarily due to loss of muscle mass.
  • Sex: Men typically have higher BMR due to greater muscle mass and lower body fat percentages. Check your BMI here.
  • Genetics: Some people naturally have faster or slower metabolisms.
  • Hormones: Thyroid function, cortisol, and other hormones significantly impact metabolic rate.
  • Body Temperature: Fever and cold exposure can temporarily increase BMR.

Frequently Asked Questions

Does BMR decrease with age?

Yes. As we age, our metabolic rate tends to slow down, largely due to a loss of muscle mass (sarcopenia). Resistance training and adequate protein intake can help mitigate this decline by preserving and building lean tissue.

Can I increase my BMR?

The most effective way to increase your BMR is to build muscle through resistance training. Muscle tissue is more metabolically active than fat tissue, meaning it burns more calories even when you are sleeping. High-intensity interval training (HIIT) can also temporarily boost metabolism post-exercise through the "afterburn effect" (EPOC).

Why is BMR important for weight loss?

Knowing your BMR gives you a baseline for calorie planning. If you consistently eat below your BMR, your body may adapt by slowing down your metabolism (metabolic adaptation), making weight loss harder in the long run and potentially causing hormonal issues. It is usually safer to create a caloric deficit from your TDEE, not your BMR.

How accurate are these calculator estimates?

Calculated BMR is an estimate with about 10% margin of error for most people. Individual variances in genetics, medications, hormonal health (especially thyroid function), and body composition can affect your actual metabolic rate. Use the result as a starting point and adjust based on your real-world progress over 2-4 weeks.

Related Health Tools

Check out these other tools to help manage your fitness journey: