Calculate your Body Mass Index (BMI), ideal weight, body fat percentage, and Basal Metabolic Rate (BMR). Supports both metric and imperial units with gender-specific calculations.
Enter your details to calculate BMI and other metrics
BMI Categories
Underweight0 - 18.5
Normal18.5 - 25
Overweight25 - 30
Obese Class I30 - 35
Obese Class II35 - 40
Obese Class III40 - 40+
These calculations are estimates and may not be accurate for athletes, elderly, pregnant women, or individuals with certain health conditions. Always consult a healthcare professional for personalized advice.
Why Use Our BMI Calculator?
Our comprehensive BMI calculator goes beyond simple body mass index calculations. It provides a complete health assessment including your ideal body weight using multiple formulas (Devine, Robinson, Miller, Hamwi), estimated body fat percentage, and your Basal Metabolic Rate (BMR) with three different calculation methods. Whether you're starting a fitness journey, monitoring your health, or simply curious about your body composition, our calculator provides all the essential metrics in one place with detailed explanations via tooltips.
Frequently Asked Questions
What is BMI and how is it calculated?
BMI (Body Mass Index) is a simple calculation using your height and weight. The formula is: BMI = weight (kg) / height (m)². For imperial measurements, it's: BMI = (weight (lbs) x 703) / height (inches)². BMI provides a numerical value that categorizes you into underweight (<18.5), normal weight (18.5-24.9), overweight (25-29.9), or obese (30+).
What's the difference between the ideal weight formulas?
Each formula was developed at different times with different populations. Devine (1974) is most commonly used in medicine. Robinson (1983) gives more conservative estimates. Miller (1983) tends to give higher ideal weights. Hamwi (1964) is one of the oldest. We recommend comparing results from multiple formulas rather than relying on just one.
Which BMR formula should I use?
Mifflin-St Jeor (1990) is generally considered the most accurate for most people. Harris-Benedict is a classic formula but may overestimate for overweight individuals. Katch-McArdle is best for athletic individuals as it uses lean body mass, but requires knowing your body fat percentage.
How accurate is the body fat percentage estimate?
Our body fat percentage uses a BMI-based formula that provides a reasonable estimate but has limitations. It's most accurate for average adults and may be less reliable for very muscular individuals, the elderly, or those with unusual body compositions. For precise measurements, consider methods like DEXA scans, hydrostatic weighing, or professional body composition analysis.
Why do I need to enter my age and gender?
Age affects body fat percentage calculation and BMR. Gender is crucial because men and women have different base values in ideal weight formulas, different healthy body fat ranges, and different metabolic rates. All three BMR formulas and the body fat estimation require gender for accurate calculations.