Described here are devices and methods for measuring a distance in an airway. In some instances, the devices may comprise an outer shaft and an inner shaft that is slidably disposed in a lumen of the outer shaft. An expandable stopper may be positioned at a distal end of the inner shaft, which may be configured to engage a carina of a patient. The device may comprise one or more alignment markings and one or more displacement markings that may be used to measure a distance between a distal tip of an endotracheal tube and the carina. In some variations, measurement may be facilitated by the use of an alignment guide that may attach to a predetermined portion of an endotracheal tube.
