BMR Calculator
Estimate your Basal Metabolic Rate (calories burned at rest).
Your Basal Metabolic Rate
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calories / day
Calculated using
About Basal Metabolic Rate (BMR)
Your Basal Metabolic Rate (BMR) is the number of calories your body needs to perform its most basic, life-sustaining functions if you were at complete rest for 24 hours. These functions include breathing, blood circulation, nutrient processing, cell production, and temperature regulation.
For more comprehensive information on metabolism and energy expenditure, you can consult trusted health organizations like the Mayo Clinic or the National Institutes of Health (NIH).
BMR accounts for the largest portion of your total daily energy expenditure (TDEE), typically 60-75%. Knowing your BMR can be a starting point for determining your overall daily calorie needs for weight maintenance, loss, or gain when combined with your activity level.
BMR Formulas Used:
- Mifflin-St Jeor Equation (1990): Considered one of the most accurate formulas for estimating BMR in healthy adults.
- Men:
(10 * weight in kg) + (6.25 * height in cm) - (5 * age in years) + 5 - Women:
(10 * weight in kg) + (6.25 * height in cm) - (5 * age in years) - 161
- Men:
- Revised Harris-Benedict Equation (1984): An older formula, still widely used, though it may slightly overestimate BMR in some individuals compared to Mifflin-St Jeor.
- Men:
88.362 + (13.397 * weight in kg) + (4.799 * height in cm) - (5.677 * age in years) - Women:
447.593 + (9.247 * weight in kg) + (3.098 * height in cm) - (4.330 * age in years)
- Men:
- Katch-McArdle Formula: This formula is based on Lean Body Mass (LBM) and can be more accurate if you know your body fat percentage reliably.
- BMR =
370 + (21.6 * Lean Body Mass in kg) - Lean Body Mass (LBM) = Weight in kg * (1 - (Body Fat % / 100))
- BMR =
Factors Influencing BMR
Several factors can affect your BMR:
- Body Composition: Muscle tissue burns more calories at rest than fat tissue. Individuals with more muscle mass tend to have a higher BMR.
- Age: BMR generally decreases with age, primarily due to loss of muscle mass.
- Sex: Men typically have a higher BMR than women, largely because they tend to have more muscle mass and less body fat.
- Weight and Height: Larger individuals (both taller and heavier) generally have a higher BMR because they have more tissue to maintain.
- Genetics: Genetic factors can play a role in your metabolic rate.
- Hormones: Hormonal imbalances (e.g., thyroid hormones) can significantly impact BMR.
- Diet: Severe calorie restriction or fasting can lower BMR as the body adapts to conserve energy.
- Body Temperature: Fever can increase BMR.
- Climate: People living in very cold or very hot climates may have a slightly higher BMR.
Understanding these factors can provide context to your BMR reading. For further reading on how lifestyle impacts metabolic rate, resources like the Harvard T.H. Chan School of Public Health offer valuable insights.
Frequently Asked Questions (FAQ)
What's the difference between BMR and RMR?
Basal Metabolic Rate (BMR) is the minimum calories needed at complete rest, often measured under strict laboratory conditions after fasting. Resting Metabolic Rate (RMR) is similar but less strict, usually measured after a short rest and may be slightly higher than BMR. For practical purposes, they are often used interchangeably.
Which BMR formula is most accurate?
The Mifflin-St Jeor equation is generally considered the most accurate for the general adult population. The Katch-McArdle formula can be more accurate if you have a precise body fat percentage measurement, as it accounts for lean body mass.
How can I use my BMR?
Your BMR is the starting point for calculating your Total Daily Energy Expenditure (TDEE), which is your BMR multiplied by an activity factor. TDEE helps you determine how many calories you need to eat to maintain, lose, or gain weight. You can use our Advanced Calorie Calculator (TDEE) to find your TDEE.
Can I increase my BMR?
Yes, to some extent. Building more muscle mass through strength training is one of the most effective ways to increase your BMR, as muscle burns more calories at rest than fat. Regular physical activity and avoiding severe calorie restriction can also help maintain a healthy metabolic rate.