BMI ranges For most adults, an ideal BMI is in the 18.5 to 24.9 range. For children and young people aged 2 to 18, the BMI calculation takes into account age and gender as well as height and weight. If your BMI is:
• below 18.5 – you're in the underweight range
• between 18.5 and 24.9 – you're in the healthy weight range
• between 25 and 29.9 – you're in the overweight range
• between 30 and 39.9 – you're in the obese range
BMI takes into account natural variations in body shape, giving a healthy weight range for a particular height. As well as measuring your BMI, healthcare professionals may take other factors into account when assessing if you're a healthy weight. Muscle is much denser than fat, so very muscular people, such as heavyweight boxers, weight trainers and athletes may be a healthy weight even though their BMI is classed as obese.
Your ethnic group can also affect your risk of some health conditions. For example, adults of Asian origin may have a higher risk of health problems at BMI levels below 25.
You should not use BMI as a measure if you're pregnant. Get advice from your midwife or General Practitioner if you're concerned about your weight.