The Kármán Line lies at an altitude of 100 kilometres (62 miles) above the earth's sea level, and commonly represents the boundary between the Earth's atmosphere and outer space.
An atmosphere does not abruptly end at any given height, but becomes progressively thinner with altitude. Also, depending on how the various layers that make up the space around the Earth are defined (and depending on whether these layers are considered part of the actual atmosphere), the definition of the edge of space could vary considerably: If one were to consider the thermosphere and exosphere part of the atmosphere and not of space, one might have to extend the boundary to space to at least 10,000 km (6,200 mi) above sea level.
The amount of lift required at any given point can be calculated by the equation: L=12ρv2SCL, where:
Wikipedia (https://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line)