International Morse Code (ITU Standard)
Complete ITU International Morse Code reference with timing rules, character mappings, and historical context.
International Morse Code, standardized by the ITU, is the global standard for Morse communication. It differs from American Morse (landline telegraph) which used different character patterns.
Timing Rules
One dot duration defines the unit. A dash lasts three units. The space between dots and dashes within a character equals one unit. Between letters: three units. Between words: seven units.
Full Character Set
| Char | Code | Char | Code | Char | Code |
|---|---|---|---|---|---|
| 0 | ----- | 1 | .---- | 2 | ..--- |
| 3 | ...-- | 4 | ....- | 5 | ..... |
| 6 | -.... | 7 | --... | 8 | ---.. |
| 9 | ----. | A | .- | B | -... |
| C | -.-. | D | -.. | E | . |
| F | ..-. | G | --. | H | .... |
| I | .. | J | .--- | K | -.- |
| L | .-.. | M | -- | N | -. |
| O | --- | P | .--. | Q | --.- |
| R | .-. | S | ... | T | - |
| U | ..- | V | ...- | W | .-- |
| X | -..- | Y | -.-- | Z | --.. |
| . | .-.-.- | , | --..-- | ? | ..--.. |
| ' | .----. | ! | -.-.-- | / | -..-. |
| ( | -.--. | ) | -.--.- | & | .-... |
| : | ---... | ; | -.-.-. | = | -...- |
| + | .-.-. | - | -....- | _ | ..--.- |
| " | .-..-. | $ | ...-..- | @ | .--.-. |
Distress Signal
SOS is transmitted as ... --- ... with no spaces between letters. It does not stand for "Save Our Ship" — it was chosen for simplicity and unmistakable recognition.