<P> The elevation of 8,848 m (29,029 ft) was first determined by an Indian survey in 1955, made closer to the mountain, also using theodolites . It was subsequently reaffirmed by a 1975 Chinese measurement of 8,848.13 m (29,029.30 ft). In both cases the snow cap, not the rock head, was measured . In May 1999 an American Everest Expedition, directed by Bradford Washburn, anchored a GPS unit into the highest bedrock . A rock head elevation of 8,850 m (29,035 ft), and a snow / ice elevation 1 m (3 ft) higher, were obtained via this device . Although it has not been officially recognised by Nepal, this figure is widely quoted . Geoid uncertainty casts doubt upon the accuracy claimed by both the 1999 and 2005 surveys . </P> <P> A detailed photogrammetric map (at a scale of 1: 50,000) of the Khumbu region, including the south side of Mount Everest, was made by Erwin Schneider as part of the 1955 International Himalayan Expedition, which also attempted Lhotse . An even more detailed topographic map of the Everest area was made in the late - 1980s under the direction of Bradford Washburn, using extensive aerial photography . </P> <P> On 9 October 2005, after several months of measurement and calculation, the Chinese Academy of Sciences and State Bureau of Surveying and Mapping officially announced the height of Everest as 8,844.43 m (29,017.16 ft) with accuracy of ± 0.21 m (8.3 in). They claimed it was the most accurate and precise measurement to date . This height is based on the highest point of rock and not the snow and ice covering it . The Chinese team also measured a snow - ice depth of 3.5 m (11 ft), which is in agreement with a net elevation of 8,848 m (29,029 ft). The snow and ice thickness varies over time, making a definitive height of the snow cap impossible to determine . </P> <P> It is thought that the plate tectonics of the area are adding to the height and moving the summit northeastwards . Two accounts suggest the rates of change are 4 mm (0.16 in) per year (upwards) and 3 to 6 mm (0.12 to 0.24 in) per year (northeastwards), but another account mentions more lateral movement (27 mm or 1.1 in), and even shrinkage has been suggested . </P>

What is the present height of mount everest