Why GPS needs 4 satellites, not 3 #Shorts

Added: 2026-05-19

[00:00:00]GPS needs four satellites to find you.

[00:00:02]Three should be enough. Here's why it isn't. Each GPS satellite tells your phone its distance. Think of it as a sphere. You're somewhere on this surface.

[00:00:13]Two satellites give you a circle of possibilities.

[00:00:16]Three satellites narrow it to two points. One is usually somewhere absurd, underground or in space.

[00:00:24]So, you have your location. So, why a fourth? Because all of this depends on your phone knowing the time to within a billionth of a second.

[00:00:33]Your phone's clock isn't that precise.

[00:00:36]So, the fourth satellite solves two things at once. Where you are and what time it actually is. Every time you find your location, your phone is also syncing to atomic time.

[00:00:47]The fourth satellite isn't really for finding you. It's for fixing your watch.

[00:00:50]Follow for one curious thing every day.