BMI Calculator

Calculate your Body Mass Index and find your healthy weight range.

BMI is a screening tool, not a diagnostic. Consult a healthcare professional for a comprehensive health assessment. This tool does not provide medical advice.

Your BMI

Underweight
<18.5 Normal
18.5–24.9 Overweight
25–29.9 Obese
≥30

Healthy weight range for your height:

Based on BMI 18.5–24.9 (WHO Normal weight range)

How It Works

Enter your weight and height in metric or imperial units. The tool instantly calculates your BMI, classifies it (Underweight, Normal, Overweight, or Obese), and shows your healthy weight range.

**BMI Calculator — Know Your Body Mass Index**

Body Mass Index (BMI) is a widely used screening tool to categorise weight status relative to height. Developed by Belgian mathematician Adolphe Quetelet in the 19th century, BMI has become the standard first-line assessment for weight-related health risk in clinical and public health settings.

**BMI Formula**

Metric: BMI = Weight (kg) / Height (m)²
Imperial: BMI = 703 × Weight (lbs) / Height (inches)²

**BMI Categories (WHO)**

| BMI Range | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25 – 29.9 | Overweight |
| 30 and above | Obese |

For Asian populations, the WHO recommends lower cut-offs: Overweight at BMI ≥23, Obese at BMI ≥27.5, due to higher health risks at lower BMIs.

**What BMI Tells You (and What It Doesn't)**

BMI is a useful screening metric but has significant limitations:

*Limitations:*
- Does not distinguish between muscle and fat. A muscular athlete may have a high BMI but very low body fat.
- Does not measure fat distribution. Visceral fat (around organs) is more dangerous than subcutaneous fat, and BMI doesn't differentiate.
- Less accurate for elderly people (who lose muscle mass) and children.
- Varies in accuracy across different ethnic groups.

*Better metrics to use alongside BMI:*
- Waist circumference (>80cm for women, >94cm for men indicates risk)
- Waist-to-hip ratio
- Body fat percentage
- DEXA scan for accurate body composition

**Healthy Weight Range Calculation**

Our calculator shows your healthy weight range based on BMI 18.5–24.9 for your specific height. This gives you a concrete weight target rather than just a category label.

**BMI for Children**

Adult BMI categories do not apply to children. Paediatric BMI is assessed using age- and sex-specific percentile charts. A child at or above the 95th percentile is considered obese; 85th–95th percentile is overweight.

Frequently Asked Questions

A BMI of 18.5–24.9 is considered healthy for most adults. For Asian populations, 18.5–22.9 may be a more appropriate healthy range.

BMI can overestimate obesity in athletes because muscle is denser than fat. An athlete may have a high BMI while having low body fat. Body fat percentage measurement is more accurate for athletes.

Overweight is BMI 25–29.9; obese is BMI 30+. Both categories carry increased health risks compared to normal weight, with obesity carrying higher risk for type 2 diabetes, cardiovascular disease, and certain cancers.

No. Adult BMI categories don't apply to children. Children's weight is assessed using age- and sex-specific BMI-for-age percentile charts from healthcare providers.

A combination of caloric deficit (eating less than you burn), regular physical activity (150+ minutes/week of moderate exercise), and sustainable dietary changes is the evidence-based approach to weight loss.