BMI Calculator
BMI Calculator — calculate your Body Mass Index instantly in metric or imperial units. Free, private, no signup. Understand your weight category in seconds.
About BMI Calculator
The BMI Calculator gives you your Body Mass Index in seconds — a widely used health screening metric that tells you whether your weight falls within a healthy range for your height. Enter your height and weight in either metric or imperial units and get your BMI result and weight category instantly, with no account or download required.
Body Mass Index was developed as a simple, population-level screening tool for weight-related health risks. It is used by healthcare providers, fitness professionals, insurance underwriters, and public health researchers as a first-pass indicator of whether weight may be contributing to health issues. While it is not a diagnostic tool, a BMI outside the normal range is often a signal that more detailed health assessment is warranted.
The calculation is straightforward: BMI equals weight in kilograms divided by height in meters squared. For imperial inputs, the tool converts automatically — you do not need to do any unit math yourself. The result falls into one of four standard WHO categories: underweight (below 18.5), normal weight (18.5–24.9), overweight (25–29.9), or obese (30 and above).
It is important to understand BMI in context. The metric was designed to describe populations, not individuals. A muscular athlete may have a BMI in the overweight range despite having low body fat. Conversely, someone with low muscle mass and high fat may have a normal BMI despite being metabolically unhealthy. BMI also does not account for where body fat is distributed — which is a significant factor in cardiovascular risk. For a complete picture of your health, BMI is a starting point, not a conclusion.
This tool is designed for adults aged 18 and over. Pediatric BMI requires age- and sex-specific percentile charts and should not be assessed using standard adult ranges.
All calculations run entirely in your browser. No health data is transmitted or stored. Free, private, and available on any device.
Frequently asked questions
Body Mass Index (BMI) is calculated by dividing your weight in kilograms by the square of your height in meters. It provides a quick screening metric for weight categories: underweight (below 18.5), normal (18.5–24.9), overweight (25–29.9), and obese (30 and above).
BMI is a useful screening tool but does not account for muscle mass, bone density, age, or gender. Athletes with high muscle mass may show a high BMI despite being healthy. Always consult a healthcare professional for a full assessment.
Yes. The BMI calculator supports both metric (kg/cm) and imperial (lbs/ft-in) units, so you can use whichever measurement system you are comfortable with.
The standard BMI categories are: Underweight (below 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), and Obese (30 and above). These ranges are defined by the World Health Organization and are widely used in clinical settings.