BMR Calculator: How to Calculate Your Basal Metabolic Rate for Weight Management and Fitness Goals

Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest — the energy required to keep your heart beating, lungs breathing, and body temperature stable. Knowing your BMR is the foundation of any effective weight management, muscle-building, or fitness plan because it tells you the minimum calories your body needs each day. Use the BMR Calculator at Today Calculator to find your number instantly.

How BMR Is Calculated

The most commonly used formula for calculating BMR is the Mifflin-St Jeor equation, which was developed in 1990 and is considered more accurate than the older Harris-Benedict equation:

Gender	Mifflin-St Jeor Formula
Male	BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age(y) + 5
Female	BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age(y) − 161

For example, a 30-year-old woman who weighs 68 kg (150 lbs) and is 165 cm (5’5″) tall has a BMR of approximately 1,417 calories per day. A 35-year-old man who weighs 82 kg (180 lbs) and is 178 cm (5’10”) tall has a BMR of approximately 1,781 calories per day.

You do not need to do the math by hand — the BMR Calculator computes it for you in seconds. You just need your weight, height, age, and gender.

BMR vs TDEE: What Is the Difference?

BMR is often confused with TDEE (Total Daily Energy Expenditure), but they are different:

Metric	What It Measures	Includes Activity?	Use For
BMR	Calories at complete rest	No	Baseline calorie needs
TDEE	BMR + daily activity + exercise + digestion	Yes	Weight loss/maintenance/gain planning

To calculate your TDEE, multiply your BMR by an activity factor:

• Sedentary (little exercise): BMR × 1.2
• Lightly active (1-3 days/week): BMR × 1.375
• Moderately active (3-5 days/week): BMR × 1.55
• Very active (6-7 days/week): BMR × 1.725
• Extra active (athlete/physical job): BMR × 1.9

Once you have your BMR from our BMR Calculator, use the Calorie Calculator to get your full TDEE and daily calorie targets, and the Body Fat Calculator to track your body composition alongside your calorie goals.

Using BMR for Weight Goals

Once you know your BMR and TDEE, you can set your calorie targets:

• To lose weight: Eat 300-500 calories below your TDEE (not below your BMR — going below BMR for extended periods slows metabolism)
• To maintain weight: Eat at your TDEE level
• To gain muscle: Eat 200-300 calories above your TDEE with adequate protein intake

Important: Never eat below your BMR for extended periods. Your BMR represents the energy your vital organs need to function. Undereating below this level can lead to metabolic adaptation, hormonal disruption, and nutrient deficiencies.

Factors That Affect Your BMR

• Age: BMR decreases about 1-2% per decade after age 20 due to muscle loss
• Muscle mass: More muscle = higher BMR (muscle burns more calories than fat at rest)
• Gender: Men typically have higher BMR due to more muscle mass and larger body size
• Genetics: Some people naturally have faster or slower metabolisms
• Hormones: Thyroid function significantly impacts BMR
• Temperature: Extreme cold or heat can temporarily raise BMR

Track how your BMR changes over time with our BMR Calculator, monitor your BMI for overall weight category, and use the Heart Rate Calculator to optimize your exercise intensity for fat burning and cardiovascular health.