Calculate your Body Mass Index instantly. Find out if you are underweight, normal weight, overweight, or obese based on your height and weight.
A BMI (Body Mass Index) Calculator estimates whether your weight falls within a healthy range relative to your height, using a simple ratio that is widely used by doctors, insurers, and public health organizations as a quick first-pass screening tool. BMI does not directly measure body fat, but decades of population-level data show it correlates reasonably well with health risk, which is why it remains one of the most commonly used general wellness indicators despite its known limitations.
In metric units, BMI = Weight (kg) divided by Height (m) squared. In imperial units, BMI = (Weight (lb) divided by Height (in) squared) x 703. The standard adult categories are: Underweight (below 18.5), Normal weight (18.5-24.9), Overweight (25-29.9), and Obese (30 and above), though some regional health bodies use slightly adjusted cut-offs for specific populations.
Enter your height and current weight in either metric or imperial units. The calculator immediately computes your BMI value and tells you which weight category it falls into, along with the healthy weight range for your specific height for easy reference.
Example 1: A person who is 1.70 m tall and weighs 65 kg has a BMI of 65 divided by 1.70 squared, approximately 22.5, placing them in the "normal weight" category.
Example 2: A person who is 5 feet 8 inches (68 inches) tall and weighs 200 lb has a BMI of (200 divided by 68 squared) x 703, approximately 30.4, which falls into the "obese" category according to the standard adult scale.
Not directly, BMI doesn't distinguish between muscle and fat mass, so very muscular individuals may show a higher BMI despite having low body fat, while it can also underestimate fat levels in some other individuals. It remains useful as a quick, low-cost general screening tool.
It's simple, inexpensive, and correlates reasonably well with health risk at a population level, making it a practical first-pass screening tool, even though more precise methods exist for individual body composition assessment.
No, children and teens use age- and sex-specific BMI percentiles rather than the fixed adult categories, since healthy body composition changes significantly throughout growth and development.
Some health organizations recommend adjusted BMI thresholds for certain populations (such as lower cutoffs for some Asian populations), since research has shown health risk can begin at somewhat different BMI levels across different groups.
Consider it a starting point for a broader conversation with a healthcare provider, who can assess your health more completely using additional factors like waist circumference, body composition, and overall lifestyle, rather than relying on BMI alone.
Yes, factors like where fat is stored on the body (especially abdominal fat), muscle mass, age, and overall fitness level can mean two people with an identical BMI have quite different actual health risk profiles.
There's no strict rule, but checking every few months alongside other health metrics like waist circumference is generally more useful than frequent daily checks, since BMI is meant to track general trends rather than day-to-day fluctuations.
No, BMI says nothing about diet quality, fitness level, blood pressure, cholesterol, or other important health markers, so someone can have a normal BMI while still having underlying health issues that BMI alone would never reveal.
BMI was created in the 1830s by a Belgian mathematician studying average body proportions across a general population, long before it was adapted decades later as a simple clinical screening tool, which explains why it was never designed to capture individual body composition precisely.
No, BMI categories are not designed for pregnancy, since healthy weight gain during pregnancy follows a different pattern; doctors use separate pregnancy weight-gain guidelines based on pre-pregnancy BMI instead of applying the standard adult categories during pregnancy itself.
Some health guidelines suggest a slightly higher healthy BMI range for older adults, since a bit of extra weight can be protective against frailty and illness later in life, which is different from the stricter ranges typically recommended for younger, generally healthier adults.
Yes, pairing BMI with waist circumference, body fat percentage, and general fitness indicators such as resting heart rate gives a much more complete view of health than any single number, since each measurement captures something the others miss.