BMI Calculator
Enter your height and weight to get your body mass index, the CDC weight category for adults and the weight range that counts as healthy at your height.
Your BMI
28.3
Overweight by the CDC categories for adults (25 to less than 30). At your height, the healthy-weight range (BMI 18.5 to under 25) is 108 to 145 lb.
| Weight | 165 lb |
|---|---|
| Height 64 in, squared | 4,096 in² |
| Weight ÷ height squared | 0.04028 |
| × 703 (CDC factor for pounds and inches) | 28.32 |
| BMI, one decimal | 28.3 |
| Category | BMI |
|---|---|
| Underweight | Less than 18.5 |
| Healthy weight | 18.5 to less than 25 |
| Overweight | 25 to less than 30 |
| Class 1 obesity | 30 to less than 35 |
| Class 2 obesity | 35 to less than 40 |
| Class 3 obesity (severe obesity) | 40 or greater |
BMI is a screening measure. It does not tell fat from muscle and bone, and the CDC says that for one person it should be considered together with other factors.
This is general information, not medical advice. Talk to a doctor about your own numbers.
How this is calculated
Body mass index is weight divided by height squared. The CDC gives two versions of the same formula: kilograms divided by meters squared, or pounds divided by inches squared, times 703.
Example: 165 pounds at 5 feet 4 inches (64 inches). 64 × 64 = 4,096. 165 ÷ 4,096 × 703 = 28.32, a BMI of 28.3, which is in the overweight range. In metric: 75 kg at 1.63 m is 75 ÷ 2.6569 = 28.23, a BMI of 28.2.
The calculator shows one decimal and cuts off the rest instead of rounding. The CDC’s limits sit exactly on tenths (18.5, 25, 30), so a BMI of 24.96 shows as 24.9 and stays in the healthy-weight row where it belongs, rather than showing 25.0 next to the wrong label.
CDC categories for adults
For adults 20 and older the CDC uses the same categories regardless of age, sex or race:
| Category | BMI |
|---|---|
| Underweight | Less than 18.5 |
| Healthy weight | 18.5 to less than 25 |
| Overweight | 25 to less than 30 |
| Class 1 obesity | 30 to less than 35 |
| Class 2 obesity | 35 to less than 40 |
| Class 3 obesity (severe obesity) | 40 or greater |
The healthy weight range for your height is the weight at a BMI of 18.5 up to the last whole pound (or kilogram) below a BMI of 25. At 5 feet 4 inches that is 108 to 145 pounds.
What BMI cannot tell you
The CDC calls BMI a screening measure and notes that it does not distinguish between fat, muscle and bone. For one person, the CDC says, BMI should be considered together with other factors; a doctor can do that. This page does not cover pregnancy.
Children and teens
For ages 2 through 19 the adult categories do not apply. The CDC compares a child’s BMI with other children of the same age and sex and reports a BMI-for-age percentile: under the 5th percentile is underweight, the 5th to under the 85th is a healthy weight, the 85th to under the 95th is overweight, and the 95th or above is obesity. The calculator shows the BMI number for a child but leaves the percentile to the CDC Child and Teen BMI Calculator, which uses the CDC growth charts.
Sources
Checked against the sources below on .
Questions people ask
What is a healthy BMI?
For adults 20 and older the CDC counts a BMI of 18.5 to less than 25 as a healthy weight. Under 18.5 is underweight, 25 to under 30 is overweight, and 30 or more is obesity.
How do I calculate BMI by hand?
Divide your weight in pounds by your height in inches squared, then multiply by 703. For 165 pounds at 5 feet 4 inches: 165 ÷ (64 × 64) × 703 = 28.3.
What is a healthy weight for 5 feet 4 inches?
108 to 145 pounds, which is a BMI of 18.5 to under 25. At 150 pounds the BMI is 25.7.
What is class 3 obesity?
A BMI of 40 or greater, which the CDC also calls severe obesity. Class 1 obesity is a BMI of 30 to under 35 and class 2 is 35 to under 40.
Is BMI accurate if I have a lot of muscle?
BMI cannot tell fat from muscle and bone, the CDC says, so a high number does not show where the weight comes from. For one person, BMI should be considered with other factors.
Can I use the adult BMI chart for my child?
No. For ages 2 through 19 the CDC uses BMI-for-age percentiles: the 85th to under the 95th percentile is overweight and the 95th or above is obesity. The CDC Child and Teen BMI Calculator gives the percentile.