BMR Calculator
Calculate your Basal Metabolic Rate to understand your body's calorie needs at rest.
Mifflin-St Jeor is considered more accurate for most people.
About Basal Metabolic Rate (BMR)
Basal Metabolic Rate (BMR) represents the minimum amount of energy (calories) your body needs to perform its most basic functions while at complete rest. These functions include breathing, circulation, cell production, nutrient processing, and maintaining body temperature.
Your BMR accounts for approximately 60-75% of your total daily calorie expenditure, making it the largest component of your energy requirements. Understanding your BMR is essential for effective weight management and nutrition planning.
BMR Formula
Mifflin-St Jeor Equation
For males:
BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5
For females:
BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161
Currently considered the most accurate for most people.
Harris-Benedict Equation
For males:
BMR = 13.397 × weight in kg + 4.799 × height in cm - 5.677 × age in years + 88.362
For females:
BMR = 9.247 × weight in kg + 3.098 × height in cm - 4.330 × age in years + 447.593
The original equation, still widely used but may overestimate BMR slightly.
Total Daily Energy Expenditure (TDEE)
Your BMR is just one component of your total daily calorie needs. To calculate your Total Daily Energy Expenditure (TDEE), you need to multiply your BMR by an activity factor:
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary | BMR × 1.2 | Little or no exercise, desk job |
| Lightly active | BMR × 1.375 | Light exercise 1-3 days per week |
| Moderately active | BMR × 1.55 | Moderate exercise 3-5 days per week |
| Very active | BMR × 1.725 | Hard exercise 6-7 days per week |
| Extra active | BMR × 1.9 | Very hard exercise, physical job or training twice a day |
Factors Affecting BMR
- Age: BMR typically decreases with age due to loss of muscle mass and hormonal changes.
- Body composition: Muscle tissue requires more energy to maintain than fat tissue. Higher muscle mass leads to higher BMR.
- Gender: Men generally have higher BMRs than women due to greater muscle mass and less body fat.
- Genetics: Inherited traits can influence metabolism by up to 10%.
- Hormones: Thyroid hormones, growth hormone, and testosterone all influence BMR.
- Climate: Living in very cold or very hot environments can increase BMR as the body works harder to maintain core temperature.
- Fasting or severe calorie restriction: Can decrease BMR by up to 30% as the body conserves energy.
- Pregnancy and lactation: Increase BMR due to the additional energy demands.
Using BMR for Weight Management
Understanding your BMR can help with effective weight management:
- Weight maintenance: Consume calories equal to your TDEE (BMR × activity factor).
- Weight loss: Create a calorie deficit by consuming less than your TDEE. A deficit of 500-1000 calories per day will lead to approximately 1-2 pounds of weight loss per week.
- Weight gain: Create a calorie surplus by consuming more than your TDEE. A surplus of 250-500 calories per day will support muscle growth when combined with resistance training.
Note: It's generally not recommended to consume fewer calories than your BMR for extended periods, as this can lead to metabolic adaptation, nutrient deficiencies, and loss of muscle mass.