BMI Calculator

Use this calculator to check your body mass index (BMI) and find out if you're at a healthy weight. You can also use this tool to check your child's BMI.

Medically Reviewed by Elfred Landas, MD on

What is Body Mass Index (BMI)?

Body Mass Index (BMI) is a measurement of body weight in relation to height. It provides a quick and easy method to estimate body fat and screen a person’s weight category: underweight, healthy weight, overweight, or obese.

How is Body Mass Index (BMI) calculated?

So how does the BMI calculator work? You can check your BMI by calculating your height and body weight. To compute an adult’s BMI, divide your weight in kilograms by your height in meters squared (m²).

For adults, a BMI between 18.5-24.9 falls within normal or healthy weight. A BMI of 25.0 or more is overweight, while a BMI below 18.5 is underweight.

Why should I check or measure my Body Mass Index (BMI)?

Knowing your BMI via tools such as a BMI calculator allows you to keep your body fat ratio in check in relation to your height, and lets you know if you are at risk of developing other diseases. A healthy BMI generally leads to a happier and healthier life, while high BMI is associated with the risks of being overweight, including developing Type 2 diabetes, heart disease, and high blood pressure.

Being aware of your BMI allows you and your health provider to make more informed decisions about your health.

Does a high body mass index (BMI) pose a serious health risk?

BMI can be a screening tool, but it does not diagnose the body fatness or health of an individual. To determine if BMI is a health risk, a healthcare provider performs further assessments. Such assessments include skinfold thickness measurements, evaluations of diet, physical activity, and family history.

Obesity: What are its risk factors?

If you have a BMI of [30.0 and above], you are categorized as obese. Obesity carries effects on the body, and people who are obese are at risk of higher mortality, as well as developing certain health conditions such as:

– Type 2 diabetes

– High LDL cholesterol, low HDL cholesterol, or unhealthy blood lipid levels

– Coronary heart disease


– Gallbladder disease


– Sleep apnea and breathing problems

– Chronic inflammation and increased oxidative stress


– Clinical depression, anxiety, and other mental health conditions

Underweight: What are its risk factors?

Underweight: What are its risk factors?

If your BMI falls [under 18.5], you are underweight. When you weigh much less than your ideal weight, you are also at risk for developing other illnesses because of nutrition deficiencies and a weak immune system. You may develop the following health conditions:

– Malnutrition

– Anemia

– Osteoporosis from a lack of calcium and Vitamin D

– Fertility problems from irregular menstrual cycles

– Higher risk of surgery complications

– Stunted growth and other development issues in children and teenagers

Is Body Mass Index (BMI) a good indicator of body fat?

While BMI and your level of body fat may share a strong correlation, no two people have the same level of body fat – even if they may end up having the same BMI results.

The difference sometimes boils down to body type, age, sex, and level of fitness. Even at the same BMI, athletes will have less body fat than those who are not athletes, older people will have more body fat than younger people, and women will likely have more body fat than men.

A trained healthcare provider should perform appropriate health assessments to evaluate an individual’s health status and risks.


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