BMI after 65
In older adults, being underweight is linked with frailty, falls and slower recovery from illness, and several large studies have found the lowest risk at a BMI somewhat above 25. Many clinicians therefore accept a BMI of about 23–30 after 65. Unplanned weight loss at this age is always worth discussing with a doctor.
BMI with age under 20
For ages 2 to 19, the calculator compares BMI with others of the same age and sex and reports a percentile. Enter the age and sex to switch automatically to these children’s charts. From 20 onwards, the adult categories apply.
Adult BMI categories
From the age of 20, everyone uses the same World Health Organization categories, whatever their sex or age:
| BMI (kg/m²) | Adult category (WHO) |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy weight |
| 25.0 – 29.9 | Overweight |
| 30.0 – 34.9 | Obesity class I |
| 35.0 – 39.9 | Obesity class II |
| 40 or more | Obesity class III |
BMI in middle age
Between about 40 and 65, many adults gain around half a kilogram a year while slowly losing muscle. The BMI categories stay the same, but because fat rises faster than BMI shows, this is the age when checking your waist and blood pressure alongside BMI is most useful.
Healthy weight in kilograms by height
The weight in kg at the bottom (BMI 18.5) and top (BMI 24.9) of the healthy range, and where obesity begins (BMI 30):
| 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 |