An individual is overweight when their BMI is between 25.0-29.9. Obesity is defined as a BMI greater than 30.0. Many web sites have calculators to measure BMI (for example, http://www.cdc.gov/healthyweight/assessing/bmi/). Measuring body fat may be done via skin-fold-thickness measurement, waist-to-hip-circumference ratio, and neutral buoyancy (water displacement) measurements. BMI is not used for children under 2 years of age, and instead growth charts should be used to identify any weight issues.