Can you climb Everest without oxygen?

Yes, but very few do. To the end of 2025 the Himalayan Database lists 221 ascents without supplementary oxygen, by 188 different people, about 1.6% of all ascents of Everest, and spring 2026 added at least three more, by Bartek Ziemski, Kristin Harila and Marcelo Segovia. Reinhold Messner and Peter Habeler were the first, on 8 May 1978, when many scientists thought it impossible. Two years later Messner climbed the North Face alone, without oxygen, during the monsoon.

Why almost everyone uses it

At the summit the air holds about a third of the oxygen it does at sea level. Bottled oxygen makes climbers faster and warmer, and in Alan Arnette's analysis of the Himalayan Database, climbers with oxygen were about twenty times more likely to reach the top. Without it, every step above 8,000 m26.247 ft is slower, the cold bites harder, and the risk of frostbite, altitude illness and fatal exhaustion climbs steeply, even for the most experienced climbers.

Who should try

Only climbers who have already been above 8,000 m26.247 ft without oxygen on easier peaks, know exactly how their body reacts, and have the support to come down fast. For anyone else, bottled oxygen is safety equipment, not a shortcut. How many oxygen bottles do I need on Everest? has the sums, and the guide chapter Supplementary oxygen explains how the systems work.

Sources: the Himalayan Database peak ascents report for Everest, no oxygen, 1950 to 2025; Everest by the Numbers: 2026 Edition, Alan Arnette.