Visibility Distance Calculator
Calculate the distance to the visible horizon from your helm height. Determine how far you can see other vessels, lights, and landmarks.
Results
Visualization
How It Works
The distance to the horizon in nautical miles equals 1.17 times the square root of the eye height in feet. For two objects (your eye and a target), the geographic range is the sum of both horizon distances. Navigation lights have a nominal range (visible at a standard distance in clear conditions), but the actual range is limited by geographic range. At 8 feet eye height, your horizon is only about 3.3 nm. Higher helm positions on larger boats provide significantly better visibility.