This article reviews the benefits and limitations of some of the different anthropometric measures to assess the health risks of obesity. Those covered are the body mass index, the waist-to-hip ratio, waist circumference and the waist-to-height ratio. The latter has the potential to be globally applicable to different ethnic populations and to children and adults. The suggested boundary values of 0.5 and 0.6 are used in a shape chart and shape calculator, described here, to indicate different levels of health risk in adults and children. A simple message from this work is ‘keep your waist circumference to less than half your height’.