What device is used to measure a person's shoe size, including width?

The Brannock device is specifically designed to measure both the length and width of a person's foot to determine their shoe size accurately. This tool features a sliding heel cup and adjustable measurement arms that help in capturing precise dimensions necessary for fitting shoes correctly. It addresses the need for an accurate shoe fitting process, ensuring customers find comfortable and properly sized footwear.

In comparison, a caliper is typically used for measuring small distances and is not intended for fitting shoes. A sizer may refer to various informal tools or guides but lacks the standardized accuracy of the Brannock device. Alternatively, a measuring tape can measure the length of the foot but does not provide the comprehensive width measurements that are crucial for a proper shoe fit. This makes the Brannock device the most suitable and accurate tool for measuring shoe sizes.