BMR Calculator
Calculate your Basal Metabolic Rate to find out how many calories your body burns at rest using two proven scientific formulas.
What is Basal Metabolic Rate (BMR)?
Your Basal Metabolic Rate (BMR) is the number of calories your body requires to carry out basic life-sustaining functions while at complete rest. These functions include breathing, blood circulation, cell production, nutrient processing, and maintaining body temperature.
BMR accounts for approximately 60-75% of your total daily calorie expenditure, making it the single largest component of your energy needs. Understanding your BMR is the foundation for calculating how many calories you need each day, whether your goal is weight loss, maintenance, or muscle gain.
Several factors influence your BMR, including your age, gender, weight, height, body composition, and genetics. Men typically have a higher BMR than women due to greater muscle mass, and BMR naturally decreases with age as muscle mass declines.
How to Calculate BMR: Two Proven Formulas
Our calculator uses two well-established scientific formulas to estimate your BMR:
Mifflin-St Jeor Equation (Recommended)
Men: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) + 5
Women: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) - 161
The Mifflin-St Jeor equation, developed in 1990, is considered the most accurate BMR formula for the general population by the American Dietetic Association.
Harris-Benedict Equation (Revised)
Men: BMR = (13.397 x weight in kg) + (4.799 x height in cm) - (5.677 x age) + 88.362
Women: BMR = (9.247 x weight in kg) + (3.098 x height in cm) - (4.330 x age) + 447.593
Originally developed in 1919 and revised in 1984, the Harris-Benedict equation is one of the most widely referenced BMR formulas. It tends to estimate slightly higher than Mifflin-St Jeor.
How to Increase Your BMR
While some factors affecting BMR are beyond your control (age, genetics), there are several evidence-based strategies to boost your metabolic rate:
- Build muscle mass: Muscle tissue burns 6-7 calories per pound per day at rest, compared to only 2-3 calories per pound for fat. Strength training is the most effective way to increase your BMR.
- Eat enough protein: Protein has the highest thermic effect of food (20-30% of calories consumed), meaning your body burns more energy digesting protein than carbs or fat.
- Avoid extreme diets: Very low calorie diets can slow your metabolism by 20-30%. Aim for a moderate deficit of 300-500 calories below your TDEE.
- Get quality sleep: Sleep deprivation can reduce BMR and increase hunger hormones. Aim for 7-9 hours per night.
- Stay hydrated: Studies show that drinking water can temporarily boost metabolism by 24-30% for about an hour.
BMR vs. RMR: What Is the Difference?
BMR and RMR (Resting Metabolic Rate) are often used interchangeably, but there is a subtle difference. BMR is measured under strict conditions (complete rest, fasting, controlled temperature), while RMR is measured under less restrictive conditions and is typically 10-20% higher than BMR. For practical purposes, the difference is minimal, and both provide useful estimates of your resting energy needs.
Frequently Asked Questions
What is BMR?
BMR (Basal Metabolic Rate) is the number of calories your body needs to perform basic life-sustaining functions like breathing, circulation, and cell production while at complete rest. It represents the minimum energy your body requires to survive.
What is the difference between BMR and TDEE?
BMR is the calories burned at complete rest, while TDEE (Total Daily Energy Expenditure) includes BMR plus all additional calories burned through daily activities, exercise, and the thermic effect of food. TDEE is always higher than BMR.
Which BMR formula is more accurate?
The Mifflin-St Jeor equation is considered the most accurate for the general population, according to the American Dietetic Association. The Harris-Benedict equation tends to overestimate by about 5% but is still widely used as a reference.
Should I eat below my BMR?
No, you should not eat below your BMR. Your body needs at least your BMR calories to maintain basic functions. Eating below your BMR can lead to muscle loss, metabolic slowdown, nutrient deficiencies, and hormonal imbalances.
How can I increase my BMR?
Build muscle through strength training, eat enough protein, get adequate sleep, stay hydrated, and avoid extreme calorie restriction. Muscle tissue burns more calories at rest than fat tissue, so increasing lean mass is the most effective approach.