BMI Calculator
Body mass index.
Body mass index.
This is a general estimate for information only — not medical advice. Everyone is different, so check with a qualified healthcare professional before making decisions about your health.
How to use BMI Calculator
- Switch between metric and imperial units
- Enter your height and weight
- Read your BMI and its weight category
About BMI Calculator
The BMI Calculator turns your height and weight into a Body Mass Index and updates the moment you type, showing the number to one decimal place beside its weight category. You can enter measurements in metric (centimeters and kilograms) or imperial (feet, inches, and pounds), and a units toggle switches between the two and recalculates instantly, so there's no manual conversion to do.
The categories it reports are the standard adult ranges used by the CDC and WHO: under 18.5 is underweight, 18.5 to 24.9 is normal weight, 25 to 29.9 is overweight, and 30 or higher is obese. Those adult thresholds are the same for men and women, so a single calculation covers everyone — whether you were looking for a BMI calculator for women, for men, or just for yourself. It's built for adults; BMI for children and teens is read differently, against age-and-sex percentiles.
Because BMI is only a general screen, it can't see muscle mass or body composition, which is worth keeping in mind when you read your number. The tool is completely free with no sign-up and no usage limits, and it runs entirely in your browser: your height and weight are never sent to a server or stored anywhere, so your measurements stay private on your own device.
Frequently asked questions
- Is the BMI Calculator free to use?
- Yes, it is 100% free with no account, sign-up, or limits on how many times you can use it.
- Is my data uploaded or stored?
- No. All calculations happen locally in your browser, and your height and weight are never sent to a server or saved anywhere.
- How is BMI calculated?
- BMI is your weight in kilograms divided by the square of your height in meters. For imperial units we use 703 times your weight in pounds divided by your height in inches squared.
- What do the BMI categories mean?
- Under 18.5 is Underweight, 18.5 to 24.9 is Normal weight, 25 to 29.9 is Overweight, and 30 or above is Obese.
- Can I switch between metric and imperial units?
- Yes. Use the units dropdown to toggle between metric (cm and kg) and imperial (ft, in, and lb), and the BMI recalculates instantly.
- Does this use the CDC BMI ranges for adults?
- Yes. The weight categories match the standard ranges the CDC and WHO use for adults, so your result lines up with a CDC adult BMI chart. BMI itself is the same formula everywhere; only how the number is interpreted differs for adults versus children.
- Is there a separate BMI calculator for women?
- No. The BMI formula and the adult weight categories are identical for women and men, so this one calculator works for both. Sex, muscle mass, and body composition aren't part of the BMI number, which is why it is a screen rather than a complete health assessment.
- What is a healthy BMI for a woman?
- For adults, a BMI of 18.5 to 24.9 is the normal-weight range for women and men alike. Because BMI ignores muscle, body-fat distribution, age, and pregnancy, treat it as a general guide and check with a healthcare professional about your own situation.
- Can I use this to check a child's or teen's BMI?
- This tool uses the fixed adult categories. For anyone under 20, BMI is compared against age- and sex-specific percentiles instead of fixed ranges, so use a dedicated child or teen BMI-for-age chart for accurate results.
- Is BMI an accurate measure of health?
- BMI is a useful general screening tool, but it does not account for muscle mass, body composition, age, or sex, so consult a healthcare professional for personalized advice.