What % of oxygen will be in the air on the summit of Khan Tengri?

Contrary to popular belief, the percentage of oxygen in the air doesn’t change significantly with altitude up to about 85km from the earth! At sea level, oxygen comprises approximately 23% the air by weight and on the summit of Mount Everest it still comprises 23% of the air. So what happens – why do you feel out of breath when you are up high and why do almost all climbers need oxygen to climb Mount Everest?

The further away from sea level you are, the entire atmosphere decreases so in effect there is less air to breathe. Less air means less oxygen. So in effect it’s true that there is less oxygen the higher up you go, but there is also less nitrogen, argon and other gasses that make up the air we breathe. Nothing changes to the proportions of the gasses in the air, however one breath will deliver less oxygen to your bloodstream, hence you will feel out of breath.

At the summit of Khan Tengri at 7000m there will be approximately 48% of the oxygen that is available at sea level.

The graph below compares the amount of oxygen available in a given volume of air at altitude relative to the amount at sea level for the same volume.