BMR Calculator
Calculate your Basal Metabolic Rate instantly
BMR Calculator
Your BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest just to keep you alive. Knowing this number is the foundation of any weight loss or muscle building plan.
How to Use This BMR Calculator
- 1Enter your age, gender, height, and weight.
- 2Click Calculate to see your BMR.
- 3Learn how to interpret your BMR and use it to calculate your total energy needs (TDEE).
Understanding Your Results
The result is your BMR in calories per day. This is what you would burn if you stayed in bed all day. To maintain your weight, you need to eat more than your BMR (usually multiplied by an activity factor).
Frequently Asked Questions
Basal Metabolic Rate (BMR) is the number of calories your body burns while at complete rest to maintain basic life functions like breathing, circulating blood, and regulating body temperature. It accounts for about 60-70% of the calories you burn daily.
BMR (Basal Metabolic Rate) and RMR (Resting Metabolic Rate) are often used interchangeably, but BMR is slightly more restrictive, requiring measurement after 8 hours of sleep and fasting. RMR is less strict and is typically what most gym tests measure. For practical purposes, the numbers are nearly identical.
The most effective way to increase your BMR is to build muscle mass. Muscle tissue is metabolically more active than fat tissue, meaning it burns more calories at rest. Regular resistance training and consuming adequate protein can help boost your BMR.
Yes. As you age, you naturally lose muscle mass and your metabolic processes slow down. This causes your BMR to decrease by about 1-2% per decade after age 20. Staying active and lifting weights can help mitigate this decline.
Generally, no. Eating consistently below your BMR can put your body into 'starvation mode' (metabolic adaptation), where it slows down calorie burning to preserve energy. It can also lead to muscle loss, nutrient deficiencies, and fatigue. Aim for a deficit from your TDEE, not your BMR.
The Mifflin-St Jeor equation (created in 1990) is considered more accurate for modern populations than the older Harris-Benedict equation (1919), which tends to overestimate BMR by about 5-15%.
Thyroid hormones (T3 and T4) maximize metabolic rate. Hypothyroidism (underactive thyroid) slows down BMR, leading to weight gain and fatigue, while hyperthyroidism (overactive thyroid) speeds it up. If your BMR seems unusually low, consult a doctor.
Average BMR varies widely by height and weight. However, a typical BMR for an average American woman is around 1,400 calories/day, while for an average man it is around 1,800 calories/day.
Yes. The Mifflin-St Jeor formula is: (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5 (for men) or -161 (for women).
Surprisingly, yes. Exposure to extreme cold or heat forces your body to work harder to maintain its internal temperature (37°C), which can slightly increase your BMR.