Distance to Horizon Calculator
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
Enter Values
How to use this calculator
- Enter your height of eye above the water (or ground) in metres.
- Read the distance to the horizon in km, nautical miles and miles.
How it works
The Distance to Horizon Calculator estimates how far you can see to the true horizon from a given height — useful for lookouts, navigation and photography.
The geometric horizon distance is about 3.57 × √(height in metres), in kilometres. The higher your eye, the further the horizon. Atmospheric refraction usually bends light enough to add roughly 8% to that distance.
Worked example
Standing on deck, eye 2 m up. Horizon ≈ 3.57 × √2 ≈ 5.05 km, or about 2.7 nautical miles.
Frequently asked questions
Why can I see distant ships further than the horizon distance?
You can see tall objects beyond your own horizon because the top of the object pokes above it. The combined range is your horizon distance plus the object's horizon distance for its height.
Does this include refraction?
It's the geometric figure. Light bending in the atmosphere typically extends the visible horizon by about 8%, a bit more or less depending on conditions.
Related tools
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.