What the BMI calculator shows
The BMI calculator gives a quick adult weight-to-height estimate: underweight, normal range, overweight and obesity. It is a free self-check tool that works directly in the browser, with no sign-up and no data upload.
How to use it
- Enter height in centimeters.
- Enter weight in kilograms.
- Run the calculation and check BMI, category and the estimated healthy weight range.
BMI method
Body mass index is calculated as weight in kilograms divided by height in meters squared. The calculator shows the number, an adult category, and an approximate weight range for the entered height.
BMI is useful as a quick population-level reference, but it does not measure body fat percentage, weight distribution, muscle mass, fluid retention, or overall health.
That is why it helps to look beyond the category and notice the direction of change: whether weight is stable, and how activity, food, sleep, and wellbeing changed over recent months.
Limits and caution
Adult BMI categories are not appropriate for children, teenagers, pregnant people, highly muscular athletes, and some older adults. Those groups need different charts or individual assessment.
This is not medical advice. If weight changes quickly, symptoms are present, eating disorder concerns exist, chronic illness is involved, or you are unsure, discuss the result with a clinician.
A fuller picture comes from additional context: waist circumference, blood pressure, lab results, activity level, nutrition, health history, and how the person feels. BMI is best discussed in context rather than alone.
If the result feels worrying, do not start severe restriction on your own. It is often safer to begin with sleep, regular meals, manageable activity, and professional guidance when medical factors are present.
Privacy
Height and weight are processed locally in the browser. Use the result as a prompt to review habits, nutrition, activity, and wellbeing, not as a diagnosis.