Adding in that the Earth's radius is about 6.4 megameters, and starting with h=5 meters you get that the horizon is about 8000 metres away. So from 5 meters up

Adding in that the Earth's radius is about 6.4 megameters, and starting with h=5 meters you get that the horizon is about 8000 metres away. So from 5 meters up the horizon is about 5 statute miles away. Then to double the distance, multiply the height by 4.