SOS in Morse Code: What It Means, How to Signal It & Its History

SOS is the most recognized distress signal in the world. In Morse code, it's represented as three dots, three dashes, three dots: ... --- ...

What Does SOS Stand For?

Contrary to popular belief, SOS doesn't stand for "Save Our Souls" or "Save Our Ship." The letters were chosen because they form a distinctive, easy-to-recognize Morse code pattern that can't be confused with any other signal. The continuous sequence ... --- ... is unmistakable whether you hear it, see it, or feel it.

History of SOS

• 1905: Germany first adopted SOS as its distress signal
• 1906: The International Radiotelegraph Convention adopted SOS as the international standard
• 1908: SOS officially replaced the earlier CQD distress call
• 1912: The Titanic famously used both CQD and SOS signals during its sinking
• Today: While maritime radio has largely moved to digital systems (GMDSS), SOS remains universally understood

How to Signal SOS

With Light (Flashlight)

1. Flash three short bursts (dots)
2. Flash three long bursts (dashes — hold about 3x longer)
3. Flash three short bursts (dots)
4. Pause, then repeat

With Sound

• Three short taps, three long taps, three short taps
• Use a whistle, horn, or bang on a surface

With a Mirror

• Use a signal mirror to reflect sunlight in the SOS pattern toward rescuers

Visual Ground Signal

• Arrange rocks, branches, or fabric to spell SOS visible from the air

SOS Timing

At standard Morse speed:

• Each dot = 1 unit
• Each dash = 3 units
• Gap between dots/dashes within SOS = 1 unit
• SOS is actually sent as a single prosign (no gaps between the letters)

This means the complete SOS signal is: di-di-di-dah-dah-dah-di-di-di with no pauses between the three letter groups.

Using Your Phone to Signal SOS

The Morse Code app has a built-in SOS emergency preset. One tap starts your phone's flashlight signaling SOS automatically — useful in emergencies where you need to signal for help.

You can also use the screen flash mode if your phone doesn't have a flashlight, or switch to audio mode to emit the SOS tone pattern through your speaker.

Download free for iOS or Android.