Distance to Horizon Calculator

It scales with the square root of your eye height. From about 9 feet the horizon is roughly 3.19 nautical miles away, and from 50 feet it stretches to about 7.53 nautical miles. Doubling your height moves the horizon out by roughly 40 percent, not double.

Distance in kilometres equals 3.57 times the square root of your eye height in metres. Feet are converted to metres first (one foot is 0.3048 metres), and the result is then also shown in nautical and statute miles.

Pure geometry over a smooth Earth gives about 3.83 times the square root of height in metres. The atmosphere bends light gently downward, so the horizon sits a little farther out, and the lower 3.57 figure builds in that typical bending.

Use the height of your eyes above the water, since that is the viewpoint the horizon is measured from. A six foot person standing on deck has an eye height closer to five and a half feet, plus the deck's height above the sea.

Add the horizon distance for your own eye height to the horizon distance for the object's height. Each of you sees to the same shared point on the curve, so their sum is the range at which the object first breaks the horizon.

Yes, over flat unobstructed ground the same formula holds, which is why it also suits a beach or an open plain. Hills, trees and buildings will block your view long before the geometric horizon in most inland settings.

Results are rounded to two decimal places for display. The 3.57 coefficient is an average, so real visibility shifts with temperature layers, humidity and unusual refraction such as a mirage, which this simple model does not attempt to predict.

Nautical miles are standard for navigation and charts, statute miles are the everyday land mile, and kilometres suit metric charts. All three describe the same distance, so pick whichever matches your other instruments.

No. The height you enter is processed entirely in your browser and nothing is transmitted, so the tool stays private and continues to work offline once loaded.