Horizon Distance
Calculator
Results
- Distance to horizon (km)
- 39.103125
- Distance to horizon (miles)
- 24.297555
Travel results
| Distance to horizon (km) | 39.103125 |
| Distance to horizon (miles) | 24.297555 |
formula-map diagram
- Distance to horizon (km)
- 39.103125
- Distance to horizon (miles)
- 24.297555
Travel relationship
Formula
d = √(2Rh + h²)= 39.103125194797
Note
This result is a simplified model: it uses the displayed formula and the values you entered, ignoring traffic, weather, winds, stops, terrain, fees and individual variation. Confirm schedules, rates and allowances with the carrier or operator.
More in Travel and navigation
See all →Frequently asked questions
How is the distance to the horizon calculated?+
It uses a formula based on the observer's height above the surface and the Earth's radius, since the horizon is the point where the line of sight becomes tangent to the curved Earth.
Why does a small increase in height noticeably extend how far you can see?+
Because the relationship is roughly proportional to the square root of height, so climbing higher gives diminishing but still real returns; doubling your height increases horizon distance by about 41%, not 100%.
Does the calculator account for atmospheric refraction?+
A basic geometric calculation does not, but light bends slightly as it passes through the atmosphere, which in practice extends the visible horizon a bit farther than the pure geometric result.
Why can I sometimes see landmarks beyond the calculated horizon distance?+
Very tall objects like mountains or skyscrapers can be visible beyond your geometric horizon because their peak extends above the horizon line even though their base is hidden by the Earth's curvature.
Does this apply the same way at sea and on land?+
The underlying geometry is identical, but it's most commonly used for sea-level observers (like on a ship) since there are few obstructions; on land, buildings, hills, and trees usually limit the actual visible distance well before the geometric horizon.