How Far Is the Horizon?
Because the Earth is curved, the distance you can see to the horizon depends on how high above the surface your eyes are — whether standing on a beach, on a hill, or in an aircraft.
The Formula
d = √(2Rh + h²), where R is Earth’s mean radius (about 6,371 km) and h is your height of eye above the surface. This is a geometric approximation that ignores atmospheric refraction, which in practice extends the visible distance slightly.
For general educational and planning purposes.
Last reviewed August 2026