SOS Morse Code
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What SOS actually is
SOS in Morse Code is three dots, three dashes and three dots: ... --- ... . It is sent as one continuous signal, with no letter gaps inside it, which is why it is written as ...---... when the gaps are removed. That unbroken rhythm is part of what makes it so easy to recognise, even through noise or poor conditions.
Despite the popular stories, SOS does not stand for Save Our Souls or Save Our Ship. It was chosen because it is simple, distinctive and hard to mistake for anything else, not because its letters spell a phrase. The three letters were picked for their pattern, and the backronyms came later.
Why it was chosen
In the early twentieth century, ships and shore stations needed one distress signal that every operator would recognise, whatever language they spoke. Earlier signals varied by country and company, which caused dangerous confusion in an emergency. An international agreement settled on SOS as the single standard distress call, because it could be sent by any telegraph or radio key and recognised by ear at once.
SOS replaced earlier calls such as CQD, which the Marconi company had used. The change was not instant everywhere, and for a time both signals were heard, including from the Titanic in 1912, whose operators sent both CQD and SOS. Over time SOS won out precisely because it was simpler and belonged to no single company.
How to send SOS
By sound or radio key, send three short dots, three long dashes and three short dots, with the usual letter timing inside the groups and no extra gap between the three groups. Repeat the whole signal with a clear pause between repeats, so a listener can be sure it is a deliberate distress call and not a fragment of another message.
By light, flash the same pattern: three short flashes, three long flashes and three short flashes, again repeated with pauses. By any other on-and-off signal, the same rule applies: short, short, short, long, long, long, short, short, short. If you are using the SOS generator on this site, it plays and flashes that exact pattern for you, and it can also export it as audio.
An important warning
SOS is a real distress signal, and it should only be sent in a real emergency or in a clearly marked practice setting, such as a classroom exercise or a radio training net where everyone knows it is practice. Sending it on a live radio frequency, a public channel or any system where rescuers might respond, just to test it, can waste rescue resources and, in some places, break the law.
The tools on this site are safe for practice because nothing leaves your browser: the sound comes from your own device and the flash is your own screen. That is the right place to learn the pattern. When you know it by heart, you will also know when not to use it.
Frequently asked questions
Does SOS stand for Save Our Souls?
No, that is a backronym invented after the signal was chosen. SOS was picked because ... --- ... is simple and unmistakable, not because the letters spell a phrase.
Is SOS three letters or one signal?
It is one signal. The letters S, O and S are run together with no gaps, which is why SOS is written as ...---... as a single prosign rather than as three separate letters.
Can I send SOS with a torch?
Yes. Flash three short, three long and three short flashes, with pauses between repeats. In daylight a torch is hard to see, so sound, radio or a mirror in sunlight are usually more effective.
Should I practise SOS on a real radio?
Only in a training setting where everyone knows it is practice. On a live frequency, a real SOS can trigger a rescue response, so practise with the tools on this site or with a practice key that is not connected to a transmitter.