BMI Calculator for Women

BMI (Body Mass Index) is a measure of body fat based on your weight relative to your height. It is calculated by dividing your weight in kilograms by the square of your height in meters (kg/m²). For US units, the formula uses pounds and inches with a conversion factor: BMI = (weight in lbs × 703) / (height in inches)².

The standard BMI categories used for adult women are: Underweight (BMI below 18.5), Healthy Weight (18.5–24.9), Overweight (25.0–29.9), Obesity Class 1 (30.0–34.9), Obesity Class 2 (35.0–39.9), and Obesity Class 3 / Severe Obesity (40.0 and above). These ranges apply to women aged 20 and older.

The BMI formula and category ranges are the same for both women and men. However, women naturally carry a higher percentage of body fat than men at the same BMI, so some health professionals consider this when interpreting results. BMI is a general screening tool, not a definitive health diagnosis.

A healthy BMI for adult women is considered to be between 18.5 and 24.9. Falling within this range is associated with a lower risk of weight-related health conditions. However, BMI should be considered alongside other factors like muscle mass, age, ethnicity, and overall health history.

Yes, BMI can be misleading in certain cases. It does not distinguish between muscle and fat, so athletic women with high muscle mass may be categorized as overweight. It also does not account for where fat is distributed on the body, which can be an important health indicator. Women who are pregnant or postpartum may also get inaccurate readings.

The BMI formula itself does not change with age, but body composition does. Older women tend to have more body fat and less muscle mass at the same BMI compared to younger women. Some health guidelines suggest that a slightly higher BMI (up to 27) may be acceptable for women over 65 without increased health risk.

This calculator is designed for adult women aged 20 and older. For children and teenagers aged 2–19, a separate BMI-for-age calculator is needed, as growth patterns and healthy ranges differ significantly from adults.

It is always a good idea to consult a healthcare provider if your BMI falls outside the healthy range. Your doctor can assess your full health picture — including medical history, physical exam findings, and lab results — to give you personalized guidance. BMI alone is not a substitute for professional medical advice.