Metric formula
BMI = weight (kg) / height (m)^2 Example: 65 kg / 1.70^2 = 22.5.
BMI Formula
BMI, or Body Mass Index, is calculated from an adult's weight and height.
Imperial formula
BMI = 703 x weight (lb) / height (in)^2 Example: 703 x 180 / 69^2 = 26.6.
How to Use the BMI Calculator
- 1Choose Metric or Imperial units.
- 2Enter your height.
- 3Enter your weight.
- 4Click Calculate BMI or let the tool update after valid input.
- 5Review your BMI value, adult BMI category, healthy BMI range, healthy weight range, and formula.
- 6Copy, share, reset, or download the result if needed.
BMI Examples
Metric example
Height: 170 cm. Weight: 65 kg.
BMI = 22.5, Healthy Weight.Imperial example
Height: 5 ft 9 in. Weight: 180 lb.
BMI = 26.6, Overweight.What Is a Healthy BMI?
A healthy adult BMI is generally 18.5 to less than 25. BMI under 18.5 is categorized as underweight, 25 to less than 30 is categorized as overweight, and 30 or higher is categorized as obesity.
BMI is only a screening measure. It should be considered alongside other health factors and discussed with a healthcare professional when personal medical guidance is needed.
BMI Chart for Adults
The adult BMI chart uses fixed category ranges for most adults age 20 and older. This makes adult BMI quick to calculate from height and weight.
Children and teens need a different BMI-for-age percentile method, so they should use a dedicated child or teen BMI calculator instead.
BMI Calculator for Women and Men
The adult BMI formula is the same for women and men. The calculator does not need sex as an input because the standard BMI equation only uses height and weight.
Interpretation can still vary by person because BMI does not directly measure muscle mass, body fat percentage, fat distribution, pregnancy, age-related changes, ethnicity, or medical history.
Healthy Weight Range
The healthy weight range is calculated from your height and the adult BMI range of 18.5 to 24.9. The calculator shows this range in kilograms or pounds depending on your selected unit system.
This range is a general screening reference, not a personal target or treatment plan.
Limitations of BMI
BMI does not directly measure body fat. It also does not account for muscle mass, bone density, pregnancy, age-related muscle loss, ethnicity, body composition, or fat distribution.
Athletes may have a high BMI because of muscle mass, while some people with a normal BMI may still have health risks from other factors.
Private Browser-Only BMI Calculation
This BMI calculator runs in your browser. Height and weight are not uploaded to FreeToolsBazaar, not saved in localStorage, and not sent to a calculation API.
The page may remember only the selected unit preference so the next visit can open in metric or imperial mode.
Frequently Asked Questions
What is BMI?
BMI, or Body Mass Index, is a calculation based on height and weight. It is commonly used as a screening measure for adult weight categories.
How do I calculate BMI?
For metric units, BMI equals weight in kilograms divided by height in meters squared. For imperial units, BMI equals 703 times weight in pounds divided by height in inches squared.
What is a healthy BMI?
For most adults, a BMI from 18.5 to less than 25 is generally categorized as healthy weight.
What BMI is overweight?
For adults, BMI from 25 to less than 30 is categorized as overweight.
What BMI is obesity?
For adults, BMI of 30 or greater is categorized as obesity. This calculator also shows Class 1, Class 2, and Class 3 obesity categories.
Is BMI different for men and women?
The standard adult BMI formula and category ranges are the same for adult men and women, but interpretation can vary because body composition differs by person.
Is BMI accurate?
BMI is useful as a quick screening measure, but it is not a complete health diagnosis. It does not directly measure body fat, muscle mass, bone density, or personal medical risk.
Can children use this BMI calculator?
This calculator is designed for adults 20 and older. Children and teens need BMI-for-age percentile calculations based on age and sex.
Does this calculator store my height or weight?
No. The calculation runs in your browser. Height, weight, and BMI results are not stored in localStorage or sent to a server.
What is BMI Prime?
BMI Prime is BMI divided by 25. A BMI Prime under 1 means the BMI is below the upper end of the healthy adult BMI range.