BMI facts*
*BMI facts medical author: Melissa Conrad Stöppler, MD
- BMI stands for body mass index. BMI is calculated by a formula that takes into account both a person's height and weight.
- BMI is reported as weight in kilograms (kg) divided by height in meters squared (m2).
- BMI is useful in classification of obesity, overweight, and healthy weight.
- Obesity is generally defined as a BMI of 30 or greater, while healthy weight for adults refers to a BMI of at least 19 and less than 25.
- A BMI of 40 or more is often used to identify people who are extremely obese and at risk for serious health complications of obesity.
How Can People Use Their BMI to Evaluate Their Bodies?
When it comes to adults and children, different methods are used to find out if weight is about right for height. Adults should learn their BMI. Not all adults who have a BMI in the range labeled “healthy” are at their most healthy weight.
- Some may have lots of fat and little muscle.
- A BMI above the healthy range is less healthy for most people; but it may be fine if someone has lots of muscle, a large body frame, and little fat.
- The further one’s BMI is above the healthy range, the higher one’s weight-related risk. If a person’s BMI is above the healthy range, he or she may benefit from weight loss, especially if there are other health risk factors.
- BMIs slightly below the healthy range may still be healthy unless they result from illness.
Read more about how knowing your BMI helps with weight management »
What is BMI?
Body mass index, or BMI, is a new term to most people. However, it is the measurement of choice for many physicians and researchers studying obesity. BMI uses a mathematical formula that takes into account both a person's height and weight. BMI equals a person's weight in kilograms divided by height in meters squared (kg/m2).
What is a healthy weight?
It is important to understand what "healthy weight" means. Healthy weight is defined as a body mass index (BMI) equal to or greater than 19 and less than 25 among all people aged 20 or over. Generally, obesity is defined as a body mass index (BMI) equal to or greater than 30, which approximates 30 pounds of excess weight. Excess weight also places people at risk of developing serious health problems.
BMI chart for weight and height
The table below has already done the math and metric conversions. To use the table, find the appropriate height in the left-hand column. Move across the row to the given weight. The number at the top of the column is the BMI for that height and weight.
(kg/m2)
Weight (lb.)
9196100105110115119124129134138143167191
9499104109114119124128133138143148173198
97102107112118123128133138143148153179204
100106111116122127132137143148153158185211
104109115120126131136142147153158164191218
107113118124130135141146152158163169197225
110116122128134140145151157163169174204232
114120126132138144150156162168174180210240
118124130136142148155161167173179186216247
121127134140146153159166172178185191223255
125131138144151158164171177184190197230262
128135142149155162169176182189196203236270
132139146153160167174181188195202207243278
136143150157165172179186193200208215250286
140147154162169177184191199206213221258294
144151159166174182189197204212219227265302
148155163171179186194202210218225233272311
152160168176184192200208216224232240279219
156164172180189197205213221230238246287328
Body weight in pounds according to height and body mass index.
Below is a table identifying the risk of associated disease according to BMI and waist size.
UnderweightN/AN/A
NormalN/AN/A
OverweightIncreasedHigh
ObeseHighVery High
ObeseVery HighVery High
Extremely ObeseExtremely HighExtremely High