Interactive tool
BMI calculator
Adult BMI using NHS category labels. This is not a diagnosis and it is not for children. If weight change is sudden or unexplained, see a GP rather than chasing a number.
What do NHS BMI categories mean?
For most UK adults, NHS information groups BMI as underweight below 18.5, healthy weight 18.5 to 24.9, overweight 25 to 29.9, and obese 30 or above. Muscle, pregnancy, oedema and ethnicity all change how useful a single number is, which is why this page is a starting point, not a verdict on your health.
| BMI | Usual NHS label |
|---|---|
| Below 18.5 | Underweight |
| 18.5–24.9 | Healthy weight |
| 25–29.9 | Overweight |
| 30 or above | Obese |
NHS advice notes that people from some Black African, African-Caribbean, South Asian and other minority ethnic backgrounds may be at risk of conditions such as type 2 diabetes at a lower BMI. A GP may use lower action points (often discussed around 23 and 27.5) for those groups. Check current NHS pages rather than treating this table as a personal target.
Related guides: weight loss and obesity, type 2 diabetes.
Common questions
- Is BMI a diagnosis?
- No. BMI is a screening number from height and weight. It does not measure body fat directly and it does not replace a GP assessment.
- Why are there different thresholds for some ethnic groups?
- NHS advice is that people from some Black, Asian and other minority ethnic backgrounds are at risk of conditions such as type 2 diabetes at a lower BMI. Clinicians often use lower action points for those groups.
- Should children use this calculator?
- No. Child BMI uses age- and sex-specific charts. Ask a GP, health visitor or school nurse rather than an adult calculator.