BMR Calculator - Calculate Basal Metabolic Rate Online Free

How to Use the BMR Calculator

1. Enter your details — weight, height, age, and gender
2. Select your activity level — from sedentary (desk job) to very active (daily intense exercise)
3. Get your BMR — the calories your body burns at complete rest
4. See maintenance calories — total daily calories needed based on your activity level
5. Adjust your goal — the tool shows calories for weight maintenance, cutting, and bulking

Your BMR is the number of calories your body burns at complete rest. Use this to plan your diet and fitness goals. All data stays in your browser.

Features

• Mifflin-St Jeor equation — most accurate BMR formula
• Activity levels — from sedentary to very active
• Maintenance calories — BMR × activity multiplier
• Dual units — imperial and metric
• Weight management — bulk/cut calorie targets

Use Cases

• Weight loss planning — determine your daily calorie target for a sustainable 0.5 lb/week loss
• Muscle building — calculate the surplus needed for lean bulking without excessive fat gain
• Diet design — build a meal plan around your maintenance calories and macronutrient needs
• Fitness programming — adjust calorie intake as you become more active and your BMR changes
• Metabolic understanding — learn how age, weight, and activity level affect your daily energy needs

FAQ

What is BMR?

BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest to maintain vital functions like breathing, circulation, and cell production. It accounts for roughly 60-75% of your total daily energy expenditure.

What is the Mifflin-St Jeor equation?

It’s the most accurate formula for estimating BMR. For men: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(y) + 5. For women: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(y) - 161.

How accurate is this BMR estimate?

The Mifflin-St Jeor equation is accurate to within about 100-200 calories per day for most people. Individual metabolic rates vary based on genetics, muscle mass, and hormones.

What’s the difference between BMR and TDEE?

BMR is your resting calorie burn. TDEE (Total Daily Energy Expenditure) is BMR plus all activity — walking, exercise, digestion. Your maintenance calories = TDEE.

Does BMR change with age?

Yes. BMR decreases by roughly 1-2% per decade after age 20, primarily due to loss of muscle mass. Strength training helps maintain a higher BMR as you age.

Tips

• For weight loss, subtract 300-500 calories from your maintenance level for sustainable fat loss
• For muscle gain, add 200-300 calories above maintenance — more will add excess fat
• Recalculate your BMR every 10-15 lbs of weight change, as your numbers will shift