BMR & TDEE Calculator
Calculate your Basal Metabolic Rate and Total Daily Energy Expenditure to plan calories for weight loss, maintenance, or lean muscle gain.
BMR & TDEE Calculator
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Understanding Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE)
Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest just to maintain vital functions like breathing, circulation, and cell production. It represents the minimum energy your body needs to survive if you stayed in bed all day. BMR typically accounts for 60-75% of your total daily calorie expenditure.
Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor that accounts for exercise and daily movement. TDEE represents the total calories you burn each day including all activities - from sleeping to intense workouts. Knowing your TDEE is essential for effective weight management.
To lose weight, eat below your TDEE (calorie deficit). To gain weight, eat above your TDEE (calorie surplus). To maintain weight, match your TDEE. This calculator uses the scientifically-validated Mifflin-St Jeor equation, considered the most accurate for modern populations.
Mifflin-St Jeor BMR Formula
The Mifflin-St Jeor equation is the gold standard for calculating BMR. It accounts for weight, height, age, and sex, providing accurate estimates for most people.
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
TDEE Calculation:
TDEE = BMR × Activity Multiplier
Example:
30-year-old male | 175 cm tall | 77 kg | Moderately active
BMR = (10 × 77) + (6.25 × 175) − (5 × 30) + 5 = 1,710 calories/day
TDEE = 1,710 × 1.55 (moderate activity) = 2,651 calories/day
Daily calorie needs: ~2,651 calories to maintain weight
Activity Level Multipliers
Your activity level significantly impacts total daily calories burned. Choose the level that best describes your typical weekly activity:
Little or no exercise, desk job, minimal walking or movement throughout the day.
Light exercise or sports 1-3 days per week, some walking or standing at work.
Moderate exercise or sports 3-5 days per week, active job or regular gym sessions.
Hard exercise or sports 6-7 days per week, physically demanding job, training for competition.
Very hard exercise twice per day, training for marathon/triathlon, construction worker or athlete.
Using TDEE for Weight Management
Weight Loss
Create a calorie deficit by eating 250-1000 calories below your TDEE. A 500 calorie deficit typically results in 1 pound of fat loss per week, as 3,500 calories equals about 1 pound of fat.
Weight Gain
Create a calorie surplus by eating 250-500 calories above your TDEE. Combine with strength training to build muscle. Excessive surplus leads to fat gain, so increase gradually.
Maintenance
Eat at your TDEE to maintain current weight. Your weight should stay stable week to week. If it changes, adjust calories by 100-200 in the appropriate direction.
Body Recomposition
Eat at or slightly below TDEE while strength training. This allows simultaneous fat loss and muscle gain, though progress is slower than focusing on one goal at a time.
Factors That Influence Your BMR
Muscle Mass
Muscle tissue burns more calories at rest than fat tissue. People with higher muscle mass have higher BMRs. This is why strength training helps with weight management - it increases your resting metabolic rate even when you're not exercising.
Age
BMR decreases with age, approximately 1-2% per decade after age 30. This is partly due to muscle loss and hormonal changes. Regular exercise and strength training can slow this decline significantly.
Genetics
Some people naturally have faster or slower metabolisms due to genetic factors. However, lifestyle factors like diet and exercise have a much larger impact on TDEE than genetics alone.
Hormones & Health Conditions
Thyroid disorders, PCOS, diabetes, and other conditions can affect metabolism. If you suspect a medical issue impacting your BMR, consult a healthcare provider. Medication, stress, and sleep quality also influence metabolic rate.
Frequently Asked Questions
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest for basic functions like breathing and circulation. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor to account for exercise and daily movement. For example, if your BMR is 1,500 calories and you're moderately active, your TDEE would be about 2,325 calories (1,500 × 1.55).
How accurate are BMR and TDEE calculators?
The Mifflin-St Jeor equation used by this calculator is accurate within 10% for most people. However, individual variations exist due to genetics, muscle mass, and metabolic adaptation. Use the calculated values as a starting point, then adjust based on real-world results over 2-4 weeks. If you're not losing/gaining weight as expected, adjust calories by 100-200 in the appropriate direction.
How many calories should I eat to lose weight?
Eat 250-1000 calories below your TDEE depending on your goals. A 500 calorie daily deficit typically results in 1 pound of fat loss per week. For sustainable weight loss, aim for 1-2 pounds per week. Faster loss often leads to muscle loss and metabolic slowdown. Never eat below your BMR for extended periods without medical supervision.
Can I increase my BMR?
Yes, building muscle through strength training is the most effective way to increase BMR since muscle tissue burns more calories at rest than fat. Getting adequate sleep, staying hydrated, and eating enough protein also support a healthy metabolism. However, most BMR variation is due to body size, composition, age, and genetics.
Should I eat below my BMR to lose weight faster?
No, eating below your BMR for extended periods can cause metabolic adaptation, muscle loss, hormonal issues, and nutritional deficiencies. Your body needs BMR calories for essential functions. Instead, create a deficit by eating between your BMR and TDEE. This allows safe, sustainable weight loss while preserving muscle and metabolic health.
Why is my metabolism slowing as I lose weight?
As you lose weight, your BMR naturally decreases because a smaller body requires fewer calories to maintain. This is normal and expected. Additionally, prolonged calorie restriction can cause metabolic adaptation where your body becomes more efficient. Combat this with strength training to preserve muscle, periodic diet breaks, and gradual calorie reduction rather than aggressive deficits.
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