An apparatus for performing volume measurement of a person, animal or object, and methods of making and using the same are described. The apparatus includes first and second chambers in gaseous communication, first and second pressure sensors that measure the air pressure inside the first and second chambers, a pump configured to move air from or to the first and/or second chambers, and a control system connected to the first and second pressure sensors and the pump. The first and second chambers have a volume that is substantially constant when the internal pressure changes. The control system stores values from the first and second pressure sensors, controls air movement to and/or from the first and second chambers, blocks air transfer between the first and second chambers, and determines the volume of the person, animal or object from pressure measurements before and after an air transfer between the first and second chambers.
