Free Health Tool

BMR Calculator - Calculate Your Basal Metabolic Rate

Use this accurate online BMR calculator to calculate your Basal Metabolic Rate using the Mifflin-St Jeor BMR calculation formula.

Enter Your Details

Using the Mifflin-St Jeor equation

yrs
cm
kg

Activity Levels Explained

Choosing the right activity multiplier is key to an accurate TDEE. Be honest — most people overestimate their activity level.

Sedentary

×1.2

Desk job with little to no exercise outside of daily movement. Think office workers who drive to work and spend evenings on the couch.

Lightly Active

×1.375

Light exercise or sport 1-3 days per week. Examples: a 30-minute walk most days or one to two gym sessions per week.

Moderately Active

×1.55

Moderate exercise or sport 3-5 days per week. Examples: regular gym-goers, cyclists, or recreational sports players.

Very Active

×1.725

Hard exercise 6-7 days per week. Examples: athletes in training, people doing two-a-day workouts, or very physical hobbies daily.

Extra Active

×1.9

Very hard exercise plus a physical job, or twice-daily training. Examples: competitive athletes, construction workers who also train.

What Is BMR?

Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic physiological functions — breathing, circulation, cell production, and temperature regulation — while at complete rest.

Think of it as your body's idle fuel consumption. Even if you stayed in bed all day without moving, you would still burn this many calories just to stay alive. BMR typically accounts for 60-75% of total daily calorie expenditure.

The Mifflin-St Jeor Formula

This calculator uses the Mifflin-St Jeor equation, widely regarded as the most accurate BMR formula for the general population.

Male: (10 × kg) + (6.25 × cm) − (5 × age) + 5
Female: (10 × kg) + (6.25 × cm) − (5 × age) − 161

BMR vs TDEE — What's the Difference?

BMR is your resting calorie baseline. TDEE (Total Daily Energy Expenditure) is your actual daily calorie burn once your activity level is factored in. It is calculated by multiplying your BMR by an activity multiplier.

TDEE is the number you should use when planning your diet — whether you want to lose, maintain, or gain weight. Eating below your TDEE creates a calorie deficit; eating above it creates a surplus.

How to Use Your Results

  1. Weight loss: Eat ~500 kcal below your TDEE for ~0.5 kg/week loss.
  2. Maintenance: Match your calorie intake to your TDEE.
  3. Muscle gain: Eat ~500 kcal above your TDEE in a lean bulk.
  4. Re-calculate regularly: As your weight changes, so does your BMR.

Frequently Asked Questions

Everything you need to know about BMR, the BMR calculation formula, TDEE, and how to use this online BMR calculator for weight loss or weight gain.

How is BMR calculated?

This BMR calculator uses the Mifflin-St Jeor equation, which is considered the most accurate BMR calculation formula for adults. 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.

How accurate is this online BMR calculator?

This online BMR calculator uses the scientifically validated Mifflin-St Jeor equation and is generally accurate within 10% for most adults. However, individual metabolism varies based on genetics, muscle mass, hormones, and lifestyle factors.

What is the difference between BMR and TDEE?

Your BMR (Basal Metabolic Rate) is the number of calories your body needs at complete rest to maintain basic functions like breathing and circulation. TDEE (Total Daily Energy Expenditure) includes your daily activity level. For weight management, you should use your TDEE rather than eating at your BMR level.

Can I use this BMR calculator to lose weight?

Yes. A BMR calculator for weight loss helps you estimate your maintenance calories (via TDEE). To lose weight, you typically create a moderate calorie deficit below your TDEE. Avoid eating below your BMR for extended periods, as this may negatively affect metabolism.

Can this BMR calculator help with weight gain?

Yes. A BMR calculator for weight gain helps determine your daily calorie needs. To gain weight, especially muscle mass, you would consume calories above your TDEE while following a structured resistance training program.

Why does BMR differ for men and women?

BMR differs because men typically have a higher proportion of lean muscle mass, which burns more calories at rest. The BMR calculator for men and BMR calculator for women use slightly different constants in the formula to reflect these biological differences.

Does BMR decrease with age?

Yes. BMR naturally decreases with age due to gradual muscle loss and hormonal changes. Strength training and adequate protein intake can help slow this metabolic decline.

Is this BMR calculator suitable for children or pregnant women?

No. This calculator is designed for adults aged 18 and above. Children, teenagers, pregnant women, and breastfeeding mothers have specialized nutritional requirements and should consult a healthcare professional for personalized guidance.