BMI Calculator
Calculate your Body Mass Index from height and weight, with category guidance and a simple scale.
About BMI Calculator
Body Mass Index is a quick screening measure that relates weight to height, used by doctors and insurers as a first-pass indicator of whether someone falls in a typical healthy range. A BMI calculator removes the arithmetic from a number people revisit throughout weight-loss and fitness journeys.
BMI = weight in kilograms ÷ (height in meters)², and the tool converts metric and imperial inputs for you. Categories are under 18.5 underweight, 18.5-24.9 healthy, 25-29.9 overweight, and 30+ obese. Because BMI ignores muscle mass and body frame, very muscular people can score high despite low body fat, so treat it as a guide rather than a diagnosis.
Health-conscious adults use it to track progress over weeks and months, fitness enthusiasts pair it with other metrics to understand their body composition, and anyone under medical advice can bring the number to their doctor. It is also the standard statistic behind many population-level health studies.
How to Use
- Enter your height and weight (metric or imperial).
- Read your BMI instantly.
- See which category your score falls into.
Example
175 cm, 70 kg BMI 22.9 · Healthy weight
BMI = 70 ÷ (1.75 × 1.75) = 22.9, which falls in the healthy range of 18.5-24.9.
FAQ
Is BMI an accurate health measure?
It's a screening tool, not a diagnosis. Muscular individuals can score high despite low body fat, so treat it as a rough guide.
What are the BMI categories?
Below 18.5 is underweight, 18.5-24.9 healthy, 25-29.9 overweight, and 30+ is obesity.
Does it work for children?
Child BMI uses age-and-sex percentiles. This calculator targets adults; consult a pediatric chart for children.
Is a high BMI always a sign of poor health?
No. BMI cannot distinguish muscle from fat, so athletes and weightlifters frequently score in the overweight range with very low body fat. It is a population screening tool; individual health depends on many factors.
Should I use this calculator if I'm pregnant?
BMI standards are based on non-pregnant adults, so scores are not meaningful during pregnancy. Doctors use different weight-gain guidance for pregnancy, so ask your provider for the right target.