The metric BMI formula
BMI was designed in metric units: BMI = weight in kg ÷ (height in m × height in m). Convert centimetres to metres by dividing by 100 — 168 cm is 1.68 m.
Worked examples
- 60 kg at 165 cm: 60 ÷ (1.65 × 1.65) = 60 ÷ 2.7225 = 22.0 — healthy weight.
- 85 kg at 178 cm: 85 ÷ (1.78 × 1.78) = 85 ÷ 3.1684 = 26.8 — overweight.
- 48 kg at 163 cm: 48 ÷ (1.63 × 1.63) = 48 ÷ 2.6569 = 18.1 — underweight.
Healthy weight in kg by height
The table shows the weight in kilograms at a BMI of 18.5 (bottom of the healthy range), 24.9 (top of the healthy range) and 30 (start of obesity):
| Height | BMI 18.5 | BMI 24.9 | BMI 30 |
|---|---|---|---|
| 150 cm | 41.6 kg | 56.0 kg | 67.5 kg |
| 155 cm | 44.4 kg | 59.8 kg | 72.1 kg |
| 160 cm | 47.4 kg | 63.7 kg | 76.8 kg |
| 165 cm | 50.4 kg | 67.8 kg | 81.7 kg |
| 170 cm | 53.5 kg | 72.0 kg | 86.7 kg |
| 175 cm | 56.7 kg | 76.3 kg | 91.9 kg |
| 180 cm | 59.9 kg | 80.7 kg | 97.2 kg |
| 185 cm | 63.3 kg | 85.2 kg | 102.7 kg |
| 190 cm | 66.8 kg | 89.9 kg | 108.3 kg |
| 195 cm | 70.3 kg | 94.7 kg | 114.1 kg |
Tips for an accurate result
Weigh yourself in the morning, after using the toilet and before eating, in light clothing. Measure your height without shoes against a wall. Decimal values are fine — enter 72.4 kg or 171.5 cm if that is what you measured. Weight naturally moves by a kilogram or so through the day, so look at the trend rather than a single reading.
Need other units?
If you measure in feet, inches, pounds or stones, use the main BMI Calculator, which switches between metric, US and UK units. For the Asian BMI ranges used in India, see the BMI Calculator India.