liminfoBMR/Body Composition Calculator
Free web tool: BMR/Body Composition Calculator
BMI
22.9
Normal
BMR (Basal Metabolic Rate)
1649 kcal
Ideal Weight (Devine)
70.5 kg
About BMR/Body Composition Calculator
The BMR & Body Composition Calculator computes three key health metrics simultaneously: Basal Metabolic Rate (BMR), Body Mass Index (BMI), and Ideal Body Weight. It uses the Mifflin-St Jeor equation — the most clinically validated formula for BMR — which calculates resting caloric expenditure based on weight (kg), height (cm), age (years), and biological sex. For males: BMR = 10W + 6.25H − 5A + 5; for females: BMR = 10W + 6.25H − 5A − 161.
Dietitians, personal trainers, healthcare providers, and individuals tracking weight or planning caloric intake use BMR as the foundation for calculating Total Daily Energy Expenditure (TDEE). By multiplying BMR by an activity factor (sedentary: 1.2, lightly active: 1.375, moderately active: 1.55, very active: 1.725), you can estimate how many calories are needed to maintain current weight. BMI is calculated as weight divided by height squared (kg/m²), with WHO categories: under 18.5 (underweight), 18.5–24.9 (normal), 25–29.9 (overweight), and 30+ (obese). Ideal weight uses the Devine formula: 50 + 2.3 × (height in inches − 60) for males, 45.5 + 2.3 × (height in inches − 60) for females.
This browser-based tool accepts height in centimeters, weight in kilograms, age in years, and gender selection. Results update in real time as you type. The BMI card displays the numeric value along with the corresponding WHO weight category. The BMR card shows kilocalories per day at complete rest. The ideal weight card shows the Devine formula target in kilograms. All computations happen locally — no data is sent to any server.
Key Features
- BMR calculation using the Mifflin-St Jeor equation — the gold standard for clinical accuracy
- BMI computation with WHO weight category label (Underweight / Normal / Overweight / Obese)
- Ideal Body Weight using the Devine formula for both males and females
- Real-time updates as you change any input field
- Accepts height in cm and weight in kg with numeric input validation
- Gender-specific formulas for both BMR and ideal weight calculations
- 100% client-side processing — your health data never leaves your browser
- Dark mode support and responsive layout for use on any device
Frequently Asked Questions
What is Basal Metabolic Rate (BMR)?
BMR is the number of calories your body burns at complete rest to maintain basic physiological functions — breathing, circulation, cell production, and temperature regulation. It represents your minimum daily caloric need and serves as the baseline for all caloric intake and weight management calculations.
What formula does this BMR calculator use?
This calculator uses the Mifflin-St Jeor equation: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 (male) or −161 (female). This equation is widely considered the most accurate predictive formula for resting metabolic rate in clinical nutrition practice.
How is BMR different from TDEE?
BMR is the caloric baseline at complete rest. Total Daily Energy Expenditure (TDEE) is BMR multiplied by an activity factor to account for movement and exercise. For example, a sedentary person multiplies BMR by 1.2, while someone who exercises intensely 6–7 days a week multiplies by 1.725.
What does the BMI number mean?
BMI (Body Mass Index) is weight in kilograms divided by height in meters squared. WHO categories: below 18.5 is underweight, 18.5–24.9 is normal weight, 25–29.9 is overweight, and 30 or above is obese. Note that BMI does not distinguish muscle from fat, so athletes may have high BMI scores despite low body fat.
What is the Devine Ideal Body Weight formula?
The Devine formula estimates a medically ideal weight based on height: for males, 50 kg + 2.3 kg for each inch over 5 feet; for females, 45.5 kg + 2.3 kg for each inch over 5 feet. This formula is widely used in clinical settings for drug dosing and nutritional assessment.
Why does gender affect BMR?
Biological sex affects BMR because males typically have higher muscle mass and lower body fat percentage than females of the same height, weight, and age. The Mifflin-St Jeor equation adds +5 kcal/day for males and −161 kcal/day for females to account for these physiological differences.
How accurate is the Mifflin-St Jeor equation?
Research shows the Mifflin-St Jeor equation predicts resting metabolic rate within 10% for most people, and it outperforms the older Harris-Benedict equation in most clinical comparisons. It is recommended by the Academy of Nutrition and Dietetics as the preferred formula for estimating RMR.
Can I use this calculator for a weight loss plan?
Yes. Once you know your BMR, multiply it by your activity level to get TDEE. To lose weight, create a caloric deficit of 250–500 kcal/day below TDEE, which produces approximately 0.25–0.5 kg of fat loss per week. For personalized nutrition advice, consult a registered dietitian.