Enter your height and weight to calculate your Body Mass Index.
BMI Classification, WHO Standards
For adults, a BMI of 18.5 to 24.9 is a healthy weight, 25 to 29.9 is overweight and 30 or more is obesity (CDC and WHO). BMI is weight in kilograms divided by height in meters squared, or pounds × 703 ÷ inches squared. Enter your height and weight above to get your BMI, your category and the healthy weight range for your height.
BMI (Body Mass Index) is a screening tool that estimates body fatness based on height and weight. The formula is: BMI = weight (kg) ÷ height (m)². For imperial units: BMI = (weight in lbs × 703) ÷ height in inches². The result is a single number that places you in a WHO classification category.
First developed by Belgian mathematician Adolphe Quetelet in 1830, BMI was adopted by the World Health Organization as a global standard for classifying weight status in populations. It remains the most widely used screening tool for weight-related health risks due to its simplicity and the extensive body of research correlating BMI with health outcomes.
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Increased |
| 18.5 to 24.9 | Normal weight | Low (lowest risk) |
| 25.0 to 29.9 | Overweight | Increased |
| 30.0 to 34.9 | Obese Class I | High |
| 35.0 to 39.9 | Obese Class II | Very High |
| 40.0 and above | Obese Class III | Extremely High |
BMI Limitations
Ethnicity Adjustments
BMI vs Body Fat %
Waist Circumference
BMI Chart for Adults in Pounds
The weight at which each adult category starts, for common heights. Weights are rounded to the nearest pound.
| Height | Healthy weight (18.5 to 24.9) | Overweight from (25) | Obesity from (30) | Class 2 from (35) | Class 3 from (40) |
|---|---|---|---|---|---|
| 4'10" | 89 to 119 lb | 120 lb | 144 lb | 167 lb | 191 lb |
| 5'0" | 95 to 127 lb | 128 lb | 154 lb | 179 lb | 205 lb |
| 5'2" | 101 to 136 lb | 137 lb | 164 lb | 191 lb | 219 lb |
| 5'4" | 108 to 145 lb | 146 lb | 175 lb | 204 lb | 233 lb |
| 5'6" | 115 to 154 lb | 155 lb | 186 lb | 217 lb | 248 lb |
| 5'8" | 122 to 164 lb | 164 lb | 197 lb | 230 lb | 263 lb |
| 5'10" | 129 to 174 lb | 174 lb | 209 lb | 244 lb | 279 lb |
| 6'0" | 136 to 184 lb | 184 lb | 221 lb | 258 lb | 295 lb |
| 6'2" | 144 to 194 lb | 195 lb | 234 lb | 273 lb | 312 lb |
| 6'4" | 152 to 205 lb | 205 lb | 246 lb | 288 lb | 329 lb |
The CDC splits obesity into three classes: class 1 is a BMI of 30 to under 35, class 2 is 35 to under 40, and class 3 (sometimes called severe obesity) is 40 or higher. The categories are the same for men and women.
Worked Examples Step by Step
Imperial: 5'9" and 160 lb
Height is 69 inches, and 69 × 69 = 4,761. Multiply the weight by 703: 160 × 703 = 112,480. Divide: 112,480 ÷ 4,761 = 23.6, which is in the healthy weight range.
Metric: 1.75 m and 70 kg
1.75 × 1.75 = 3.0625. Then 70 ÷ 3.0625 = 22.9, also a healthy weight.
Near a boundary: 5'11" and 200 lb
71 × 71 = 5,041, and 200 × 703 = 140,600. 140,600 ÷ 5,041 = 27.9, overweight. To reach a BMI under 25 at this height the weight would need to be 179 lb or less. Whether that is a sensible goal is a question for your doctor, since BMI does not see muscle, bone or where fat is stored.
Children and Teens: BMI-for-Age Percentiles
For ages 2 to 19 the BMI number is calculated the same way, but it is not compared with the adult cut-offs. It is plotted on the CDC growth chart for the child's sex and exact age, and the category comes from the percentile. A BMI of 23 can be healthy for a 17-year-old and in the obesity range for an 8-year-old. That is why this calculator shows no adult category when you enter an age under 20.
| CDC category (ages 2 to 19) | BMI-for-age percentile |
|---|---|
| Underweight | Less than the 5th percentile |
| Healthy weight | 5th to less than the 85th percentile |
| Overweight | 85th to less than the 95th percentile |
| Obesity | 95th percentile or greater |
| Severe obesity | 120% of the 95th percentile or greater, or a BMI of 35 or greater |
Use the CDC child and teen BMI tool or ask your pediatrician, who will look at the growth trend over several visits rather than one reading.
Common BMI Mistakes
- Mixing units. The 703 factor only works with pounds and inches. With kilograms, use meters, not centimeters: 175 cm is 1.75 m.
- Using height in feet and inches as a decimal. 5'9" is 69 inches, not 5.9 feet.
- Reading one number as a diagnosis. BMI is a screening measure. A waist over 40 inches in men or 35 inches in women adds risk at any BMI, and very muscular people can read as overweight while carrying little fat.
- Applying adult ranges to kids. Under 20, only the percentile counts.
For a view of body composition rather than weight, try the body fat calculator or the waist-to-hip ratio calculator. Results here are estimates; talk to a doctor or dietitian before making health decisions.