What is BMI?
BMI (Body Mass Index) is a simple measure that uses your height and weight to estimate whether you're at a healthy weight. CDC describes it as a quick, safe and reliable screening measure, and uses it to place adults in four groups: underweight, healthy weight, overweight and obesity. It is a screening figure, not a diagnosis.
BMI doesn't measure body fat directly, but CDC says it is moderately to strongly associated with other measures of body fat. Use the body mass index calculator above to find your BMI instantly.
BMI formula
Metric
BMI = weight (kg) ÷ height (m)²
Example: 70 kg ÷ (1.75)² = 22.9
Imperial
BMI = (lbs × 703) ÷ height (in)²
Example: (154 × 703) ÷ (69)² = 22.7
Both are CDC's formulas (CDC, BMI Frequently Asked Questions).
BMI categories
CDC uses these BMI categories for adults 20 and older, the same for men and women (CDC, Adult BMI Categories):
| Category | BMI Range |
|---|---|
| Underweight | Below 18.5 |
| Healthy weight | 18.5 to 24.9 |
| Overweight | 25.0 to 29.9 |
| Class 1 obesity | 30.0 to 34.9 |
| Class 2 obesity | 35.0 to 39.9 |
| Class 3 obesity (severe) | 40.0 or greater |
BMI chart by height and weight
This BMI chart shows weight boundaries (in whole lbs) for each BMI category at common heights, worked out with CDC's formula and cut-offs:
| Height | Healthy (lbs) | Overweight | Obesity starts |
|---|---|---|---|
| 4'10" | 89–119 | 120–143 | 144+ |
| 5'0" | 95–128 | 129–153 | 154+ |
| 5'2" | 102–136 | 137–164 | 165+ |
| 5'4" | 108–145 | 146–174 | 175+ |
| 5'6" | 115–154 | 155–185 | 186+ |
| 5'8" | 122–164 | 165–197 | 198+ |
| 5'10" | 129–174 | 175–209 | 210+ |
| 6'0" | 137–184 | 185–221 | 222+ |
| 6'2" | 145–194 | 195–233 | 234+ |
| 6'4" | 152–205 | 206–246 | 247+ |
BMI and body fat
BMI is a ratio of weight to height, so it cannot tell fat from muscle or bone. CDC notes that people with a lot of muscle can have a BMI in the overweight or obesity range. Body fat percentage, the share of your weight that is fat tissue, measures body composition directly.
Body fat can be measured with calipers, bioelectrical impedance scales, or DEXA scans, and our body fat calculator estimates it from tape measurements. Two people can have the same BMI but very different body fat percentages, which is why BMI alone is a starting point rather than a verdict.
Healthy weight by height, men and women
Wondering what the normal weight for a 6'2 male is? CDC's healthy BMI range (18.5 to under 25) works out to 145–194 lbs at 6'2". For a 5'2 female, it is 102–136 lbs. The ranges are the same for men and women, because CDC applies one set of adult categories regardless of sex. The table shows the whole pounds and kilograms inside the healthy range at each height:
| Height | Healthy weight (lbs) | Healthy weight (kg) |
|---|---|---|
| 5'0" | 95–128 | 43–58 |
| 5'2" | 102–136 | 46–61 |
| 5'3" | 105–141 | 48–64 |
| 5'4" | 108–145 | 49–66 |
| 5'6" | 115–154 | 52–70 |
| 5'8" | 122–164 | 56–74 |
| 5'9" | 126–169 | 57–76 |
| 5'10" | 129–174 | 59–79 |
| 5'11" | 133–179 | 61–81 |
| 6'0" | 137–184 | 62–83 |
| 6'1" | 141–189 | 64–85 |
| 6'2" | 145–194 | 66–88 |
| 6'3" | 149–200 | 68–90 |
A healthy weight for a 5'2 woman is 102–136 lbs. A healthy 5'3 female weight is 105–141 lbs. Appropriate weight for 5'6: 115–154 lbs, for men and women alike.
A healthy 5'9 male weight is 126–169 lbs. Healthy weight for a 5'10 male: 129–174 lbs. 5'11 male weight healthy range: 133–179 lbs.
Healthy weight for a 6'1 male: 141–189 lbs. 6'2 ideal weight male: 145–194 lbs across the healthy BMI range. Healthy weight for a 6'3 male: 149–200 lbs.
Ranges are the whole pounds and kilograms with a BMI from 18.5 to under 25. They are not averages, and the right weight for you also depends on muscle mass and your health.
Limitations of BMI
While BMI is a useful screening tool, it has important limitations:
- Doesn't distinguish fat from muscle. CDC notes that people with a lot of muscle can have a BMI in the overweight or obesity range.
- Doesn't show where fat is carried. CDC says BMI cannot indicate where fat is located in the body; waist size (below) fills part of that gap.
- One set of cut-offs for every adult. CDC applies the same categories from age 20 regardless of age, sex or race, so BMI alone can't reflect differences in body composition between people. Children and teens use BMI-for-age percentiles instead.
- Lower threshold for some groups. NIDDK's guidance on who should be screened for diabetes treats a BMI of 23 or more as overweight for Asian Americans, against 25 for other adults.
Tip: For a more complete picture, combine BMI with a waist measurement. The National Heart, Lung, and Blood Institute says a waist of more than 40 inches (men) or 35 inches (women) increases the risk of heart disease and type 2 diabetes.
Ideal body weight formulas
Formulas such as Devine's and Robinson's give a single "ideal" weight from height and sex. They are not part of CDC's BMI guidance, and they give different answers from one another and from the BMI range above. Our ideal weight calculator shows four of them side by side.
FAQs
What is BMI?
BMI (Body Mass Index) is weight divided by height squared: kilograms over metres squared, or 703 times pounds over inches squared. It is a screening number for adults, not a diagnosis, and it can't tell fat from muscle.
How do you calculate BMI?
Using metric units: BMI = weight in kilograms ÷ (height in meters)². For example, a person weighing 70 kg and 1.75 m tall: 70 ÷ (1.75 × 1.75) = 22.9. Using imperial units: BMI = (weight in pounds × 703) ÷ (height in inches)². For example, 154 lbs and 69 inches: (154 × 703) ÷ (69 × 69) = 22.7. CDC's own example: an adult who is 5 feet 8 inches tall and weighs 200 pounds has a BMI of 30.4.
What is a healthy BMI?
CDC's healthy weight range for adults is a BMI of 18.5 to less than 25 (18.5 to 24.9 to one decimal). Below 18.5 is underweight, 25 to less than 30 is overweight, and 30 or more is obesity. BMI is one measure of health: CDC advises considering it alongside a physical exam, lab results and health behaviors.
Is BMI accurate for muscular people?
Not always. CDC notes that people with a lot of muscle can have a BMI in the overweight or even obesity range, because BMI cannot distinguish between fat, muscle and bone. For athletes, a body composition measurement (such as a DEXA scan, skinfold calipers or bioelectrical impedance) says more about body fat than BMI does.
What are the BMI categories and ranges?
CDC's BMI categories for adults 20 and older are: Underweight: below 18.5. Healthy weight: 18.5 to 24.9. Overweight: 25.0 to 29.9. Class 1 obesity: 30.0 to 34.9. Class 2 obesity: 35.0 to 39.9. Class 3 obesity (severe): 40.0 or greater. CDC applies these ranges regardless of age, sex or race.
What is the difference between BMI and body fat percentage?
BMI uses only weight and height, so it can't tell muscle from fat. Body fat percentage measures the fat itself, which is why a muscular athlete can have a high BMI and a low body fat percentage.
Is BMI different for women vs. men?
Many people search for a BMI calculator for women or a BMI calculator for men, but the BMI formula and category ranges are the same for both: CDC applies the adult categories regardless of sex. What BMI can't show is how much of a person's weight is fat, muscle or bone, which varies from one person to the next.
Can BMI change with age?
Your BMI changes only if your weight or height changes. CDC uses the same categories for all adults 20 and older. Children and teens are assessed differently, with a BMI-for-age percentile that compares a child's BMI with others of the same sex and age.
How do I know if I'm at a healthy weight?
Enter your height and weight above to see your BMI category and the healthy weight range for your height. A BMI from 18.5 to 24.9 is in CDC's healthy weight range. Waist size adds something BMI can't: the National Heart, Lung, and Blood Institute says a waist of more than 40 inches for men or 35 inches for women increases the risk of heart disease and type 2 diabetes. A doctor can put the numbers together for you.
How can I lower my BMI?
With your height fixed, BMI falls only as your weight falls. CDC's guidance: people who lose weight gradually, about 1 to 2 pounds a week, are more likely to keep it off, and adults need 150 minutes of moderate-intensity activity a week plus muscle-strengthening activity on at least 2 days. For a 5'8" adult, going from a BMI of 30 to 25 means losing about 33 lbs.
Also known as a calculadora de IMC, calculate your Body Mass Index (Indice de Masa Corporal) in any unit system. This free tool works for both imperial and metric measurements.