Distance to Horizon Calculator

Enter the values to get the distance.

How to use

  1. Enter your values in the fields above.
  2. Press Calculate to see your result instantly.
  3. Use the Share button to copy a link to your result.

About this calculator

Because the Earth curves, how far you can see before the horizon drops out of sight depends only on how high your eye is above the surface. Approximating the Earth as a sphere of radius R and using the Pythagorean relationship gives d ≈ √(2Rh), which simplifies to the practical formulas d ≈ 3.57 × √h (km, with h in meters) or d ≈ 1.22 × √h (miles, with h in feet).

Sailors, pilots, and lighthouse engineers use this to work out how far away a ship, coastline, or light can first be spotted, while photographers and hikers use it to estimate visibility from a viewpoint, and telecom engineers use the same geometry to judge line-of-sight range for cell towers and microwave links.

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