BMR Calculator – Basal Metabolic Rate
Calculate your Basal Metabolic Rate (BMR) to find how many calories your body burns at rest.
What is Basal Metabolic Rate (BMR)?
Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic life-sustaining functions while at complete rest — breathing, circulation, cell production, and temperature regulation. It represents the minimum energy required to keep you alive.
BMR accounts for roughly 60–75% of your total daily calorie expenditure, making it the single largest component of your energy needs. Even if you did nothing but sleep all day, your body would still burn this many calories.
How is BMR Calculated?
The two most widely used formulas are the Mifflin-St Jeor equation (more accurate for most people) and the Harris-Benedict equation (older but still commonly used).
Mifflin-St Jeor:
Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
For a 30-year-old woman, 65 kg, 165 cm: BMR = 10×65 + 6.25×165 − 5×30 − 161 = 1,420 calories/day.
BMR vs TDEE: What is the Difference?
BMR is your calorie floor — what you burn doing nothing. TDEE (Total Daily Energy Expenditure) multiplies your BMR by an activity factor to estimate real-world calorie needs.
If your goal is weight loss, you need to eat below your TDEE. If you want to gain muscle, you eat above it. BMR is the starting point for all these calculations.
Frequently Asked Questions
Does BMR change with age?
Yes. BMR decreases by roughly 1–2% per decade after age 20, mainly due to loss of muscle mass. Strength training can slow this decline.
Is BMR the same as resting metabolic rate (RMR)?
They are similar but not identical. RMR is slightly higher than BMR because it is measured under less strict conditions. In practice, the terms are often used interchangeably.
Can I increase my BMR?
Yes — building muscle is the most effective way. Muscle tissue burns more calories at rest than fat. Regular resistance training, adequate protein, and quality sleep all help raise your BMR over time.