BMI Calculator

Get your body mass index calculated for free

Use units: MetricImperial

Body Mass Index (BMI) is a simple calculation using your height and weight to gauge if you're at a healthy size. It's a decent screening tool to check for potential weight-related health risks, but definitely not the be-all and end-all. This BMI calculator makes it super easy to run the numbers.

What do the BMI numbers mean?

BMI classification of adults
Thinness Normal Overweight Obese
BMI<18.5 18.5≤BMI<25 25≤BMI<30 30≤BMI

But listen, if you're a muscular athlete or an older adult who's lost some muscle mass, the BMI may not be totally accurate for you. No sweat though, your doctor can advise if it applies in your case.

How to calculate BMI?

Too lazy to use the calculator? No problem, you can do it manually:

Metric BMI Formula:

BMI = weight (kg) / [height (m)]²

Or

BMI = [weight (kg) / height (cm) / height (cm)] x 10,000

Imperial BMI Formula:

BMI = weight (lb) / [height (in)]² x 703

If you're used to expressing your height in feet and inches, you can first convert feet and inches to inches.

Health Risks of High BMI

Having an overweight or obese BMI puts you at higher risk for some pretty heavy stuff like heart disease, stroke, type 2 diabetes, and certain cancers. For kids, it can cause breathing issues, fractures, high blood pressure and self-esteem troubles down the line.

Health Risks of Being Underweight

On the flip side, if your BMI falls into the underweight zone, you may face problems like nutrition deficiencies, brittle bones, immune system weaknesses, or potential growth and fertility issues. If there's no obvious reason for being extremely underweight, get it checked out by a pro - it could signal an eating disorder or other condition.

How to Stay in the Healthy Range

The World Health Organization (WHO) recommends these tips to prevent overweight/obesity:

Tracking your BMI with a calculator can help you work toward a healthy weight. But don't get too obsessed - having a balanced lifestyle is what really counts in the long run. Focus on balanced nutrition, exercise, and get professional advice if needed.