Measurement apparatus includes an elastic fabric, configured as a garment to be worn over a part of a body of a human subject. One or more conductive fibers are integrated with the elastic fabric to as to stretch together with the elastic fabric when worn over the part of the body. A controller is coupled to measure a change in an electrical property of the one or more conductive fibers in response to stretching of the elastic fabric, and to output an indication of a dimension of the part of the body based on the measured change.