SOS in Morse Code
Three dots, three dashes, three dots. The only signal that every operator, coast guard and pilot still recognises instantly.
- Signals
- 9
- Dots
- 6
- Dashes
- 3
What does SOS mean in Morse code?
SOS is the international distress signal written as ... --- ... — three dots, three dashes, three dots. It is sent as one continuous group of nine signals, which is why radio operators call it a prosign rather than three letters.
It is the one Morse sequence most people still know, and the only one that carries legal weight: under the ITU Radio Regulations, ...---... has the same distress status as the spoken word MAYDAY.
How to send SOS in Morse code
Every Morse signal is built from one time unit. A dot is one unit, a dash is three, and the gaps follow the same scale. Keep the three groups clearly separated or the receiver will read it as random letters.
| Element | Length | In SOS |
|---|---|---|
| Dot | 1 unit | 6 dots in total |
| Dash | 3 units | 3 dashes in total |
| Gap between signals | 1 unit | 8 gaps, or 2 if you use no letter gaps |
| Gap between letters | 3 units | Optional — the prosign runs continuously |
Total: about 23 units without letter gaps, 27 with them. At 20 WPM (60 ms per dot) one complete SOS lasts roughly 1.4 to 1.6 seconds — short enough to repeat several times in a row.
Why SOS and not “Save Our Souls”
SOS is not an abbreviation. The pattern was picked for purely practical reasons: it is short, perfectly symmetrical, and its rhythm stands out against ordinary traffic and static. It also reads the same upside down, which mattered on paper slips.
The “Save Our Souls” and “Save Our Ship” readings appeared afterwards, as memory aids. They are useful for remembering the signal and completely wrong as etymology — a distinction most search results get wrong.
SOS vs CQD: how the distress signal changed
- 1904The Marconi company introduces CQD — CQ (general call) plus D (distress). Operators dislike it: it is easy to confuse with ordinary CQ calls.
- 1906The International Radiotelegraphic Convention in Berlin adopts ...---... as the standard distress signal, to take effect on 1 July 1908.
- 1912Titanic operators send CQD first, then SOS, on 15 April. The disaster makes SOS the signal the public knows.
- TodaySOS remains in the ITU Radio Regulations. GMDSS and satellite beacons handle most rescues, but ...---... is still the fallback every operator is trained on.
Sending SOS without a radio
Morse is just timed on-and-off signalling, so the same rhythm works in any medium. The rule is the same everywhere: three short, three long, three short, then a pause before repeating.
Flashlight
Short flashes for dots, long for dashes. Aim at the horizon or a passing aircraft.
Whistle
Three short blasts, three long, three short. A whistle carries much further than a voice.
Tapping
Knock on a pipe, wall or hull. In collapsed structures, three taps is the standard reply to rescuers.
Mirror
Reflect sunlight in the same three-long pattern. Effective over several kilometres in daylight.
Common mistakes when sending SOS
- Running all nine signals together with no gaps at all — the receiver hears one long blur.
- Making the three dashes into one long dash. Three separate 3-unit signals, not one 9-unit signal.
- Sending SOS once and stopping. Distress traffic is repeated at short intervals until someone answers.
- Testing it on a real distress frequency. Never transmit SOS for practice on air — use a dummy load or this page's audio.
Practise SOS now
Listen to the correct rhythm first, then type ... --- ... into the translator to see it decoded back to SOS. Change the speed in the audio generator to hear how the gaps scale.
SOS in Morse code: FAQ
Is SOS an abbreviation for “Save Our Souls”?+
No. The letters do not stand for anything. SOS was chosen purely because ...---... is short, symmetrical, and hard to mistake for ordinary traffic. “Save Our Souls” and “Save Our Ship” were invented afterwards as memory aids.
Do you put spaces between the letters in SOS?+
The standard is one continuous signal: three dots, three dashes, three dots with a single-unit gap between each signal. Radio operators treat ...---... as a single prosign, not as the letters S, O and S. Many people add letter gaps when tapping or flashing SOS, and it is still recognised.
How long does it take to send SOS?+
The sequence is about 23 time units long without letter gaps and 27 with them. At 20 words per minute a dot is 60 ms, so a complete SOS lasts roughly 1.4 to 1.6 seconds.
What is the Morse code for HELP?+
HELP is .... . .-.. .--. — but it is not a distress signal. Only ...---... (SOS) and the spoken word MAYDAY carry internationally recognised distress status. If you need rescue, send SOS.
Did the Titanic send SOS?+
Yes. On 15 April 1912 the operators first sent the older CQD, then SOS. The disaster made SOS famous and pushed operators still using CQD to switch.