Outdoors & maps
Geometric horizon distance
Estimate an unobstructed horizon from height above a spherical surface.
A clear answer. Here’s how.
Uses a 6,371 km spherical Earth. Straight line-of-sight distance = sqrt(h(2R+h)); surface arc distance = R×atan(line distance/R). Also reports the geometric dip angle. Ignores atmospheric refraction, terrain, visibility and the height of a target beyond the horizon.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Observer height above surface (m)
- 2
Example result
- Straight horizon line distance (km)
- 5.04816838071
- Surface arc to horizon (km)
- 5.04816732422
- Geometric dip angle
- 0.0453992594497°