Mount Hood's snow-covered summit has varied in height. Three distinct heights are suggested by current sources: 11,239 ft (3,425.6 m) of slightly older origin, 11,240 ft (3,426 m) based on a 1993 scientific expedition, and 11,249 ft (3,429 m) a 1991 adjustment of a 1986 measurement by the U.S. National Geodetic Survey (NGS). Twelve named glaciers and snowfields are located on the peak.