BMI Calculator

Body Mass Index is calculated using weight in kilograms divided by height in meters squared (BMI = kg/m²). For imperial units, multiply weight in pounds by 703, then divide by height in inches squared. While useful for broad populations, it does not directly measure body fat or composition.

According to WHO and CDC guidelines, a healthy BMI range for most adults is between 18.5 and 24.9. A value below 18.5 indicates underweight, 25.0 to 29.9 is classified as overweight, and a BMI of 30.0 or higher falls into the obese categories.

BMI does not distinguish between muscle mass and body fat. Consequently, muscular athletes may register as overweight or obese despite having very low body fat. It also fails to account for age, biological sex, genetic background, bone density, or the distribution of visceral versus subcutaneous fat.

Health organizations recommend a lower healthy BMI threshold of 23.0 for adults of South Asian, Chinese, and Black heritage. This is because metabolic risk factors, including type 2 diabetes and cardiovascular disease, begin to accumulate at a lower body mass index in these specific ethnic populations.

To calculate BMI from stones and pounds, convert your weight entirely into pounds (one stone equals 14 pounds) or kilograms (one stone is 6.35 kg). Our calculator accepts stones and pounds directly in the imperial unit toggle, automatically performing the mathematical conversion for your convenience.

A healthy BMI is between 18.5 and 24.9 for most adults. To determine if your weight is in a healthy range, enter your height and weight into our calculator. It automatically applies the standard formulas to estimate your weight classification and healthy target weight range.

In metric units, divide your weight in kilograms by your height in centimeters divided by 100, then squared. For example, if you weigh 70 kg and stand 170 cm tall, divide 70 by 1.7 squared (2.89) to yield a standard BMI value of approximately 24.2.

No, BMI is generally inaccurate for weightlifters, bodybuilders, and individuals with high muscle mass. Because muscle tissue is denser than fat tissue, a muscular person can be classified as overweight or obese by BMI standards, even if their actual body fat percentage is exceptionally low.

For adults, a BMI from 25.0 to 29.9 is classified as overweight, while a value of 30.0 or higher is considered obese. Obesity is further divided into Class I (30.0 to 34.9), Class II (35.0 to 39.9), and Class III or severe obesity (40.0 and above).

For children and teens aged 2 to 19, health status is determined using age- and sex-specific BMI percentiles instead of fixed adult ranges. A healthy percentile is between the 5th and less than the 85th percentile on official CDC growth charts.

Yes, this condition is known as normal weight obesity or being 'skinny fat.' An individual can have a normal BMI but carry high levels of body fat and low muscle mass, which carries similar metabolic health risks to being overweight, especially if fat is stored abdominally.

BMI Prime is a ratio comparing an individual's actual BMI to the healthy upper limit of the healthy range (defined as 25.0). A BMI Prime of 1.0 represents the healthy limit. Values below 0.74 indicate underweight, while values of 1.0 to 1.19 indicate overweight, and 1.2 or higher indicate obesity.

The Ponderal Index is a measure of body composition calculated by dividing weight in kilograms by height in meters cubed. It is particularly useful for assessing body proportions in infants, tall individuals, and short statured people, as it adjusts more effectively for height variations than standard BMI.

Body Surface Area represents the calculated surface area of a human body, measured in square meters. It is estimated using formulas like Du Bois and is widely used in medical settings to determine precise drug dosages, intravenous fluid requirements, and metabolic indices.