Mount Everest

Nepal and China jointly announced a new official height for Everest on 8 December 2020. The figure of 8,848.86 m is about 86 cm above the older Chinese and Indian survey numbers.

Measured heights shift slightly with survey method and snow cover. This is the officially agreed figure.

Context

Earlier numbers for Everest came from different surveys. India's Survey of India reported 8,848 m in the 1950s, and a Chinese measurement in 2005 gave 8,844.43 m, which excluded the snow cap and used the rock height. The 2020 joint announcement settled the dispute by agreeing on a snow-top height, so the two countries now share one official number.

Surveyors combine several techniques. Teams climb to the summit with satellite positioning equipment, while others take readings from surrounding peaks using trigonometry, and the results are tied to a model of sea level called the geoid. Because the answer depends on how that sea-level surface is defined, tiny differences in method can shift the result by decimetres.

Everest is the highest point above sea level, but not the farthest from Earth's centre or the tallest from base to peak. Chimborazo in Ecuador is farther from the centre because of the planet's equatorial bulge, and Mauna Kea is taller measured from its undersea base. Everest also continues to be pushed upward by tectonic collision, at a rate of a few millimetres a year.