S in Morse Code
The letter S in Morse code is ...: three dots, sounded “di-di-dit”. So when someone asks what 3 dots mean in Morse code, the answer is the letter S, the first and last letter of SOS.
What Does S Look Like in Morse Code?
S has 3 signals (3 dots) and takes 5 timing units to send. S is the third step of the dot ladder after E and I. Three dots, three dashes and three dots in a row make the distress signal SOS. See it next to every other letter on the Morse code alphabet chart.
Words That Start With S in Morse Code
| Word | Morse code | Letters |
|---|---|---|
| SOS | ... --- ... | S O S |
| SEE | ... . . | S E E |
| STAR | ... - .- .-. | S T A R |
| SUN | ... ..- -. | S U N |
| SMILE | ... -- .. .-.. . | S M I L E |
Each word starts with .... A space separates the letters. Type any other word into the Morse code translator to hear it.
Letters Easily Confused With S
O (the opposite of S)
--- · three dashes
I (one dot fewer)
.. · two dots
H (one dot more)
.... · four dots
V (S plus a dash)
...- · three dots then a dash
E, I, S and H are one, two, three and four dots, and the number 5 is five. S also starts V, which adds one dash. For a step-by-step method, read how to identify a letter from its Morse pattern.
How to Remember S in Morse Code
Say it out loud
“Di-di-dit” is three quick, even blips. It is easy to recognise because it opens and closes SOS.
Learn it with O
S is three dots and O is three dashes. Together they form SOS, the most famous pattern in Morse code.
Drill it
Hear S against H, I and O in the Morse code practice quiz.
How Long Does S Take to Send?
S is 5 units long: 1 for each of the three dots and 1 for each of the two gaps between them. A dot is 1 unit and a dash is 3. The Morse code timing guide explains how speed changes the length of a unit.
| Speed | One unit | Time to send |
|---|---|---|
| 5 WPM | 240 ms | 1200 ms |
| 10 WPM | 120 ms | 600 ms |
| 15 WPM | 80 ms | 400 ms |
| 20 WPM | 60 ms | 300 ms |
| 25 WPM | 48 ms | 240 ms |
S in Radio and Real-World Morse
SOS
SOS is sent as ...---... with no gaps between the letters. It became the international distress signal in 1906. Read the SOS in Morse code guide.
SK: end of contact
The prosign SK (...-.-) marks the end of a contact. See Morse code prosigns.
Sierra in the NATO alphabet
On voice radio, S is spoken “Sierra”. Morse code vs the NATO alphabet compares both.
SOS by light
Three short, three long, three short flashes is SOS by torch. Practise it with the Morse code light tool.
How Efficient Is S in Morse Code?
Alfred Vail gave common letters short codes after estimating how often each letter is used. Comparing S’s share of English text with the length of its code shows how well that plan worked for this letter.
| Measure | S |
|---|---|
| Share of letters in English text | 6.3% |
| Frequency rank (of 26 letters) | 7th |
| Morse code length | 5 units |
| Other letters with the same length | A, N |
| American Morse (US landline telegraph) | ... (same as International) |
S is the seventh most common letter and takes 5 units. Three dots are fast to send and impossible to confuse with dashes, which is one reason S was paired with O in the SOS distress signal.
Frequently Asked Questions
What is S in Morse code?
S in Morse code is ..., three dots.
What does 3 dots mean in Morse code?
Three dots (...) is the letter S. Three dots, three dashes and three dots sent together (...---...) is the distress signal SOS.
How do you say S in Morse code out loud?
S is spoken “di-di-dit”: three short, even sounds.
What is the difference between S and O in Morse code?
They are opposites. S is three dots (...) and O is three dashes (---).
What does SK mean in Morse code?
SK is a prosign meaning end of contact. It is sent as ...-.-, with S and K joined together.