BMI for Women: Normal, Overweight and Obese Ranges Explained — 2026

Body Mass Index (BMI) is a screening ratio of weight to height, not a direct measure of body fat. BMI = weight (kg) ÷ height (m)². In imperial units the formula is 703 × weight (lb) ÷ height (in)². The number is the same regardless of sex for adults.

The CDC applies the same four adult categories to men and women aged 20 and older. BMI is a starting point for population-level screening, not a diagnosis for any individual.

• Underweight: BMI below 18.5
• Healthy weight: BMI 18.5 to 24.9
• Overweight: BMI 25.0 to 29.9
• Obesity: BMI 30.0 and above (Class 1: 30–34.9, Class 2: 35–39.9, Class 3: 40+)

Men and women share the same CDC adult BMI cutoffs, but men tend to carry more muscle and abdominal fat on average, so waist circumference is especially useful alongside BMI for men.

• Underweight: BMI below 18.5
• Healthy weight: BMI 18.5 to 24.9
• Overweight: BMI 25.0 to 29.9
• Obesity: BMI 30.0 and above (Class 1: 30–34.9, Class 2: 35–39.9, Class 3: 40+)

Women and men use the same CDC adult BMI categories. Women naturally carry more body fat for reproductive and hormonal health, so a slightly higher BMI can be normal; body-fat percentage adds context during training or life-stage changes.

• Underweight: BMI below 18.5
• Healthy weight: BMI 18.5 to 24.9
• Overweight: BMI 25.0 to 29.9
• Obesity: BMI 30.0 and above (Class 1: 30–34.9, Class 2: 35–39.9, Class 3: 40+)

A BMI of 25.0–29.9 is categorized as overweight. Higher BMI is generally associated with increased risk of type 2 diabetes, high blood pressure, heart disease, and certain cancers, though risk varies widely between individuals.

• Underweight: BMI below 18.5
• Healthy weight: BMI 18.5 to 24.9
• Overweight: BMI 25.0 to 29.9
• Obesity: BMI 30.0 and above (Class 1: 30–34.9, Class 2: 35–39.9, Class 3: 40+)

The CDC applies standard adult BMI classes. Obesity is BMI 30 and above, subdivided as Class 1 (30.0–34.9), Class 2 (35.0–39.9), and Class 3 (40.0 and above, sometimes called severe obesity).

Higher obesity classes are generally linked to greater risk of cardiometabolic disease, sleep apnea, and joint problems. Structured, supervised approaches are most effective — discuss options with a healthcare provider.

• Class 1: 30.0 – 34.9
• Class 2: 35.0 – 39.9
• Class 3: 40.0 and above

Standing height is the input for BMI and many other ratios, so a small error changes the result. Use a stadiometer when possible; at home, a flat wall and a hard-backed book work.

• Remove shoes and bulky clothing; stand with heels, buttocks, shoulders, and the back of the head against a flat wall.
• Keep the head level (Frankfort plane: the lower eye socket and the ear opening are horizontal) and look straight ahead.
• Take a normal breath in and stand as tall as you can; mark the wall at the top of the head with a pencil or book edge.
• Measure from the floor to the mark with a metal tape, to the nearest 0.1 cm (or 1/4 inch).
• Common errors: measuring in the evening (the spine compresses ~1–2 cm by day’s end), slouching, keeping shoes on, or compressing the hair.

BMI cannot distinguish muscle from fat, so trained athletes and very muscular people may read as "overweight" or "obese" despite low body fat. It also does not capture fat distribution, which matters for health risk.

BMI is not interpreted with adult cutoffs for children and teens (they use age- and sex-specific percentiles), and it is not a tracking tool during pregnancy. Waist circumference and body-fat percentage add useful context.