SOS in Morse Code
Learn the meaning, history, and official signal for the international distress call.
What SOS Looks Like in Morse Code
The SOS signal consists of three parts that are sent together without pauses between letters:
- S = . . . (three dots)
- O = - - - (three dashes)
- S = . . . (three dots)
In many systems, SOS is written with a bar above the letters (SOS) to indicate that they should be sent as one continuous signal without the usual spaces between letters.
Where the SOS Signal Came From
SOS is a convenient letter-name for the continuous pattern ...---...; it was not created as an abbreviation for “Save Our Souls” or “Save Our Ship.” The signal appeared in German national radio rules in 1905 and was adopted internationally at the Berlin Radiotelegraph Conference in 1906.
The 1906 rules directed ships in distress to repeat the pattern at brief intervals. The ITU history of maritime radio documents that adoption, while IMO distress-signal guidance still lists a signal made by any signalling method using the Morse group ...---....
Emergency note: modern maritime and local emergency systems include radio voice, digital selective calling, satellite alerts, beacons, and other approved signals. Use the official channel and equipment available to you; this educational browser page is not emergency equipment.
Related Topics:
How to Signal SOS Without a Radio
Flashlight
Use a flashlight to send short and long bursts of light in the ... --- ... pattern.
Whistle
Three short blasts, three long blasts, and three short blasts on a whistle or horn.
Tapping
Tap on a metal pipe or hull in the ... --- ... sequence to be heard by rescuers.
SOS Timing: Dots, Dashes and Spacing
International Morse timing uses one unit for a dot and three units for a dash. The gap between signal elements is one unit. SOS is sent as one continuous distress prosign, so the nine elements stay together without the usual three-unit letter gaps.
| Part | Pattern | Timing |
|---|---|---|
| First S | ... | Three one-unit signals |
| O | --- | Three three-unit signals |
| Final S | ... | Three one-unit signals |
Frequently Asked Questions
How many signals are in SOS?
SOS contains nine elements: six dots and three dashes, arranged as three dots, three dashes and three dots.
Does SOS mean Save Our Souls?
No. Save Our Souls and Save Our Ship are later memory phrases. The symmetrical signal was selected because it is easy to transmit and recognize.
Can SOS be sent with light or sound?
The pattern can be reproduced with a flashlight, whistle or tapping. In an emergency, use an available official emergency channel or local emergency service first; SOS is a supplementary way to attract attention.
Two timing checks for SOS
At 20 WPM, one unit is 60 ms. Each dot lasts 60 ms, each dash 180 ms, and each three-unit letter boundary 180 ms. The complete keyed pattern plus its two letter gaps lasts about 1.62 seconds.
With a flashlight, choose one steady beat as the dot unit: one beat for each short flash, three beats for each long flash, one beat inside a letter, and three beats between S and O. Repeat only when it is safe and useful.
SOS can support marine, outdoor, aviation-training, and classroom demonstrations, but it does not replace a phone call, beacon, radio distress procedure, or local emergency service.
Should SOS be written with spaces?
It is commonly displayed as ... --- ... so the three groups are readable. In operation it is recognized as one distinctive distress sequence.
How often should I repeat it?
There is no universal count for every situation. Use the applicable emergency procedure, conserve power where necessary, and listen or look for a response.
Standard and review note Timing was checked against ITU-R Recommendation M.1677, International Morse code. Reviewed August 2026.