A BMI between 18.5 and 24.9 is considered normal or healthy weight according to the World Health Organization.

What is a healthy BMI for a woman?

The healthy BMI range is the same for men and women: 18.5–24.9. However, women naturally carry a higher body fat percentage than men at the same BMI.

BMI is a useful population-level screening tool but has limitations. It does not distinguish between muscle and fat, and may misclassify muscular athletes or older adults with low muscle mass.

BMI Calculator

Enter your height and weight to calculate your Body Mass Index, see your category, healthy weight range, and how you compare to people worldwide.

Height

Weight

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BMI Scale

18.5

3040+

* Based on global WHO / NCD-RisC statistical data. Results are approximate.

What is BMI?

Body Mass Index (BMI) is a numerical value derived from a person's height and weight. It provides a simple, inexpensive screening method to categorize individuals as underweight, normal weight, overweight, or obese. Developed by Belgian mathematician Adolphe Quetelet in the 19th century, BMI was adopted by the World Health Organization as a global standard for obesity classification.

BMI does not directly measure body fat, but research shows it correlates moderately with more direct measures of body fat. It is widely used as a population-level tool to identify weight-related health risks, though individual assessment should consider additional factors.

BMI Chart for Adults

Category	BMI Range	Health Risk
Underweight	Below 18.5	Increased risk (malnutrition, osteoporosis)
Normal weight	18.5 – 24.9	Lowest risk
Overweight	25.0 – 29.9	Increased risk
Obese Class I	30.0 – 34.9	High risk
Obese Class II	35.0 – 39.9	Very high risk
Obese Class III	40.0 and above	Extremely high risk

Source: World Health Organization (WHO), 2000. What is a healthy BMI? →

How to Calculate BMI

BMI is calculated using one of two formulas depending on the unit system:

Metric: BMI = weight (kg) ÷ height² (m²)
Imperial: BMI = 703 × weight (lbs) ÷ height² (inches²)

Example (metric): A person who weighs 70 kg and is 1.75 m tall has a BMI of 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 ≈ 22.9 — Normal weight.

Example (imperial): A person who weighs 154 lbs and is 5'9" (69 inches) tall has a BMI of 703 × 154 ÷ (69 × 69) = 108,262 ÷ 4,761 ≈ 22.7 — Normal weight.

BMI Limitations

While BMI is a useful screening tool, it has well-documented limitations that are important to understand:

Muscle mass: BMI cannot distinguish between fat and muscle. Highly muscular athletes may be classified as overweight or obese despite having very low body fat.
Age: Older adults tend to have more body fat relative to BMI. A BMI at the lower end of "normal" in an elderly person may actually indicate sarcopenia (muscle loss).
Ethnicity: Research shows that people of Asian descent face higher health risks at lower BMI values. Some health authorities recommend lower thresholds (e.g., 23 for overweight) for Asian populations.
Sex: Women naturally carry higher body fat percentages than men at the same BMI. BMI does not account for this difference.
Body distribution: Where fat is stored matters. Abdominal (visceral) fat is more dangerous than fat stored in the hips and thighs, but BMI doesn't capture this distinction.

Frequently Asked Questions

A BMI between 18.5 and 24.9 is considered normal or healthy weight by the World Health Organization. This range is associated with the lowest risk of weight-related health complications for most adults.
The healthy BMI range (18.5–24.9) applies to both men and women. However, women naturally carry about 6–11% more body fat than men at an equivalent BMI, so context matters when interpreting results.
BMI is a reasonably accurate population-level indicator but less precise for individuals. Studies show it correctly identifies obesity in about 50% of cases and has a specificity of about 95%. It works best when combined with other measures like waist circumference and body fat percentage.
Yes. Some research suggests that a BMI between 25 and 27 may actually be protective in adults over 65, as being slightly heavier can help during illness recovery. Consult a healthcare provider for age-specific guidance.
Absolutely. Elite athletes and bodybuilders often have BMIs in the overweight or obese range due to high muscle mass, despite having very low body fat percentages. For muscular individuals, DEXA scans or hydrostatic weighing provide more accurate body composition measurements.
A modified version called BMI-for-age percentile is used for children and teens aged 2–19. It compares BMI to peers of the same age and sex. Our calculator is designed for adults (20+); pediatric BMI assessment requires different reference charts.