Free online BMI (Body Mass Index) calculator. Enter your height and weight to get your BMI value, see your weight category, and view the healthy weight range for your height.
| Category | BMI |
|---|---|
| Underweight | < 18.5 |
| Healthy | 18.5 – 24 |
| Overweight | 24 – 27 |
| Obese I | 27 – 30 |
| Obese II | 30 – 35 |
| Obese III | ≥ 35 |
Categories follow Taiwan MOHW standards. BMI is not suitable for pregnant women, under-18s or athletes — for reference only.
BMI = weight(kg) ÷ height(m) squared — a quick estimate of body status from height and weight. Common cut-offs are underweight <18.5, normal 18.5–24.9, overweight 25–29.9, obese ≥30 (some regions, including Taiwan, use 24/27). It's a screening reference, not a diagnosis.
BMI only sees height and weight — it can't tell muscle from fat, so athletes may read 'overweight' while having low body fat; it also doesn't suit elderly people or pregnancy. For a fuller picture, look at waist circumference and body-fat percentage too, not one number.
BMI is best for tracking your own trend over time rather than a single reading. For health decisions, rely on a medical professional. To convert height and weight units, use our unit converter.
BMI = weight(kg) ÷ height(m) squared. For 65 kg and 170 cm: 65 ÷ (1.7×1.7) ≈ 22.5.
A BMI of 18.5–24 is generally considered healthy; 24–27 is overweight and 27+ is obese, while under 18.5 is underweight.
BMI is a quick screening tool but doesn't suit pregnant women, under-18s, athletes or very muscular people. Pair it with body-fat and professional assessment.