An airway sizing apparatus (10) for determining a cross-sectional length (20) of an airway (30) of a subject (40) comprising: a guide rod assembly (50) including one or more control members (52) and a distal scale (54)； a collar assembly (70) disposed on the guide rod assembly, configured to radially expand and contract with activation of the one or more control members； wherein the collar assembly includes a collar indicator member (72) that moves linearly on the distal scale to indicate the cross-sectional length of the airway.
