BMI Calculator — Body Mass Index
What is BMI Calculator — Body Mass Index
Body Mass Index (BMI) is a number calculated from your height and weight that indicates whether you are in a healthy weight range. It is calculated by dividing weight in kilograms by the square of height in meters (kg/m²). While BMI is a useful screening tool, it does not directly measure body fat or account for age, sex, muscle mass, or bone density.
How to use
- Select Metric (cm/kg) or Imperial (ft+in/lbs) using the toggle.
- Enter your height in the height field.
- Enter your weight in the weight field.
- Read your BMI result and category instantly.
When to use it
Heading into a checkup and want a number to bring with you? Enter 175 cm and 80 kg and you get BMI = 26.1, which lands in the Overweight range (25–29.9). That gives you a concrete baseline to talk through with your doctor instead of guessing.
Frequently asked questions
What is a healthy BMI range?
A BMI between 18.5 and 24.9 is considered normal weight. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese.
Is BMI accurate for athletes?
BMI can overestimate body fat in muscular people like athletes, since muscle is denser than fat. A person with high muscle mass may have a high BMI but low actual body fat.
What is my BMI if I weigh 70 kg and am 170 cm tall?
BMI = 70 / (1.70)² = 70 / 2.89 = 24.2 — Normal weight.
Does BMI differ for men and women?
The BMI formula is the same for men and women, but the same BMI may correspond to different body fat percentages between sexes. Healthcare providers may interpret BMI results differently based on sex and age.
Can I share this tool with my inputs pre-filled?
Yes. The URL updates automatically as you type. Copy it from the address bar or use the Share button — anyone who opens the link will see your exact inputs ready to go.
Related tools
A-a Gradient Calculator
Calculate the alveolar-arterial oxygen gradient from FiO2, PaO2 and PaCO2, and compare it to the expected value for age. Free and instant.
How Old Am I? Age Calculator
Find out exactly how old you are with this free age calculator. Enter your date of birth and get your age in years, months, days, zodiac sign, and more.
Anion Gap Calculator
Calculate the serum anion gap from sodium, chloride and bicarbonate, with optional potassium and albumin correction, to screen for metabolic acidosis.