What is a healthy BMI for adults?

For adults, a BMI of 18.5 to 24.9 is classified as Normal weight. Below 18.5 is Underweight; 25–29.9 is Overweight; 30 and above is Obese. These are general guidelines from the WHO — BMI doesn't account for muscle mass, age, or ethnicity.

How is BMI calculated?

BMI = weight (kg) ÷ height² (m²). For example, someone who weighs 70 kg and is 1.75 m tall has a BMI of 70 ÷ (1.75 × 1.75) = 22.9, which is Normal weight.

Can BMI be misleading?

Yes. BMI doesn't distinguish between fat and muscle — a very muscular athlete can have a 'overweight' BMI while being extremely healthy. It also doesn't account for fat distribution (belly fat is riskier than hip fat). Use it as one indicator alongside others.

What BMI is considered obese?

A BMI of 30 or above is classified as Obese (WHO definition). Class I obesity is 30–34.9, Class II is 35–39.9, and Class III (severe) is 40+. At these levels, health risks including type 2 diabetes, cardiovascular disease and sleep apnea increase significantly.

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BMI calculator

Enter your height and weight to calculate your Body Mass Index, see your weight category, your healthy weight range and BMI Prime.

Weight (kg)

Height (cm)

⚕️ BMI is a screening tool, not a diagnosis. Consult a healthcare professional for medical advice.

Understanding your BMI

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What BMI actually measures

BMI is a ratio of weight to height squared — a quick, population-level screening tool. It correlates with body fat for most adults, but misses important nuance like muscle mass, bone density and fat distribution.

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Athletes and muscle

A muscular athlete can have a BMI of 27 or higher while carrying very little body fat. For this reason, military and sports medicine often use body fat percentage or waist circumference instead.

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BMI Prime explained

BMI Prime is your BMI divided by 25 (the upper limit of normal). A value of 1.0 = upper boundary of Normal. Values above 1.0 indicate overweight or obesity; below 0.74 indicates underweight.

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Ethnicity & age

Asian populations tend to face health risks at lower BMI thresholds (23 vs 25). Older adults may be healthier at the high end of Normal. Some experts recommend BMI 22–27 as the real target for older adults.

BMI categories (WHO definition)

Category	BMI range	Health risk
Underweight	< 18.5	Increased
Normal weight	18.5 – 24.9	Low
Overweight	25.0 – 29.9	Moderate
Obese class I	30.0 – 34.9	High
Obese class II	35.0 – 39.9	Very high
Obese class III	≥ 40.0	Extremely high

BMI calculator FAQ

Is a BMI of 25 overweight?

A BMI of exactly 25 sits at the boundary — 25.0 is technically the start of the Overweight range (25.0–29.9). At 24.9 you're Normal. In practical health terms, a BMI of 25 with healthy lifestyle habits carries very little additional risk compared to 24.

What is a healthy BMI for a woman vs a man?

The standard BMI ranges (18.5–24.9 normal) apply equally to men and women. However, women naturally carry more body fat than men at the same BMI. Some research suggests optimal BMI for women may be 21–23 and for men 22–24, but the WHO categories remain the most widely used benchmark.

How accurate is BMI for children?

This calculator is for adults (18+). For children and teens, BMI is assessed differently using age- and sex-specific percentiles — a BMI value alone isn't enough. Use a CDC pediatric BMI calculator for those under 18.

Can I have a normal BMI but still be unhealthy?

Yes — "skinny fat" or normal-weight obesity is a real condition where someone has a normal BMI but high body fat percentage and low muscle mass. Waist circumference and body fat % give a fuller picture. A BMI in the normal range is a positive sign but not a guarantee of good health.