Mount Everest's Official Height Was Wrong for 65 Years, Until Nepal and China Finally Agreed in 2020

Everest is 8,848.86 metres above sea level. That figure only became official on 8 December 2020, when the foreign ministers of Nepal and China pressed a button at the same moment during a livestreamed ceremony and revealed a number neither country had published before. For 65 years, the world had been climbing, filming and writing about a mountain whose exact height nobody could actually agree on.

The gap was never really about the mountain growing overnight, though it does grow, slowly. It was about what counted as the top. China's 2005 figure measured bare rock, stripping out the snow and ice cap that every climber actually stands on. Nepal, and most of the rest of the world, measured the highest point a person can physically reach, ice included. That single difference in definition created a 4.4-metre disagreement that ran for a decade and a half, printed differently in atlases depending on which side of the border published them.

Nepal ended its dependence on foreign survey data in 2017, training its own geodetic team to carry GPS receivers and gravity meters to the summit alongside oxygen bottles and rope. A Nepali team completed the climb and survey in May 2019; a Chinese team followed in May 2020, delayed a year by the pandemic. The two governments then reconciled both data sets and, instead of each publishing a separate number again, announced one figure together for the first time in the mountain's surveying history.

The 2019–2020 expedition data was also used to settle a separate worry. After the 2015 Gorkha earthquake, some geologists suspected Everest might have lost height as the crust shifted. The new survey found no evidence of that — if anything, the mountain has kept rising. Geologists put the long-term growth rate at roughly 4 millimetres a year, driven by the Indian tectonic plate, which continues pushing north into the Eurasian plate at about 5 centimetres annually, the same force that built the entire Himalayan range over the last 50 million years.

What this means for trekkers

You don't need to summit to see why the number matters. Most trekkers get their first real look at Everest from Kala Patthar or along the Everest Base Camp trek itself, and for travellers short on time or altitude tolerance, an Everest Base Camp helicopter tour covers the same view in a single day. Either way, the mountain in front of you is 86 centimetres taller than every map printed before December 2020.

Sources: The Kathmandu Post, “It’s official: Mt Everest is 8,848.86 metres tall,” 8 December 2020; CNN, “Mount Everest: China and Nepal agree on height after years of dispute.”

Cover photo: Megaurab09 via Wikimedia Commons (CC BY-SA 4.0).