BMI Calculator
Free BMI calculator with metric and imperial units. See your body mass index, category and the healthy weight range for your height in seconds.
How this BMI calculator works
Body mass index (BMI) is your weight in kilograms divided by your height in meters squared. In US units the formula is weight in pounds × 703 ÷ height in inches squared. The calculator updates as you type and shows where you land on the standard adult ranges used by the CDC and the World Health Organization.
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25 – 29.9 | Overweight |
| 30 and above | Obesity |
What BMI can and can't tell you
BMI is a quick screening number, not a diagnosis. It doesn't know how much of your weight is muscle, so strong, athletic people often score as “overweight” while carrying little body fat. It also says nothing about where fat is stored, which matters for health. Pair it with your waist measurement, how you feel, your energy and your bloodwork, and talk to your doctor before making big changes.
BMI ranges for children and teens are age and sex specific percentiles, so this calculator is for adults 20 and older.
Next steps
If you want to change your weight, the most useful next number is your daily calorie target. Try the calorie calculator, then read our guide on how to calculate a calorie deficit and these 29 ways to lose weight naturally.
Frequently asked questions
What is a healthy BMI?
For adults, a BMI from 18.5 to 24.9 is classed as a healthy weight range.
Is BMI accurate for athletes?
Not very. BMI can't tell muscle from fat, so muscular people often score higher than their body fat would suggest.
Can I use this BMI calculator for kids?
No. Children and teens use age- and sex-specific BMI percentiles, so ask a pediatrician or use a child BMI chart.
Disclaimer: Results are estimates for healthy adults and are not medical advice.