How high up in space can you go before you cant breath?

Answer 1

If you go above about 12,000 feet above sea level, you should have supplemental oxygen, because you are no longer getting enough to keep your mind clear. Above about 18,000 feet, it will become very difficult to remain coherent, and above about 25,000 feet, you will quickly become hypoxic and lose consciousness. This is one of the reasons why mountain climbing is dangerous; climbers above 18,000 feet who refuse to wear an oxygen mask are more likely to make stupid and fatal mistakes.

If you experience a rapid decompression - for example, in an aircraft that loses cabin pressure - you have only a minute or two of "useful consciousness" unless you can quickly don an oxygen mask.

Answer 2

The threshold where you can no longer breathe is typically around 50 kilometers (31 miles) above Earth's surface. At that altitude, the lack of atmospheric pressure makes inhaling oxygen impossible, resulting in a rapid loss of consciousness.

Answer 3

The threshold where you can no longer breathe is typically around 50 kilometers (31 miles) above Earth's surface. At that altitude, the lack of atmospheric pressure makes inhaling oxygen impossible, resulting in a rapid loss of consciousness.