In this article
Every letter of the alphabet can be sent down a wire using just two signals: a short one (dot) and a long one (dash). Morse code was built for the telegraph in the 1800s and is still used by radio amateurs, pilots checking a beacon and people who like puzzles. What makes it clever is not the dots and dashes. It is the order in which the codes were handed out.
The whole alphabet
International Morse code has 26 letters, 10 digits and a handful of punctuation marks. Here are all the letters. Look for the pattern: the shortest codes belong to letters you meet all the time.
| Letter | Code | Letter | Code | Letter | Code |
|---|---|---|---|---|---|
| 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 | --.. |
Dot is a short signal, dash a long one. Digits are always five signs: 1 is .----, 5 is ..... and 0 is -----.
Time, not symbols, is what counts
A dash is not just “a different symbol”. It is a signal held three times as long as a dot, and the silences have exact lengths too. Without them, ...---... could not be told apart from other letter splits. All timing is counted in one basic unit, the length of a dot.
Everything else follows from these five numbers. Skilled operators can hear the gaps as clearly as the signs.
S is three dots plus two gaps: 1+1+1+1+1 = 5. O is three dashes plus two gaps: 3+1+3+1+3 = 11. Total 27 units.
Why common letters get short codes
Imagine a telegraph operator who has to send thousands of words a day. If the most frequent letter, E, takes 1 unit and a rare one like Q takes 13, the rare letters barely matter because they hardly appear. The result is a shorter message overall. This is the same idea behind modern file compression.
E takes 1 unit, T and I take 3, A, N and S take 5. Even the longest of these, O at 11, is not long.
Q and J take 13 units each. They appear in about one letter in a thousand, so the cost barely adds up.
Weighted by typical English letter frequencies (E 12.7%, T 9.1% and so on). The same set of codes can be about 1.7 times slower if handed out the wrong way round.
How fast is “fast”?
Speed is measured in words per minute, using the word PARIS as the standard. PARIS plus the gap after it takes exactly 50 units, so at 1 WPM a dot lasts 1.2 seconds. The faster the speed, the shorter the unit.
Labels are words per minute. At 20 WPM a dot is 60 ms and a dash 180 ms. Beginners usually learn at 5 to 10 WPM; fast operators pass 30.
Seconds are units × 0.06 at 20 WPM. Longer words take longer, but not in proportion to their letter count.
- 1Hear the rhythm, not the dotsLearn each letter as a sound pattern. “Di-dah” is A, not “dot dash”.
- 2Listen for the gapsA longer pause means a new letter. A much longer pause means a new word.
- 3Copy at a comfortable speedStart at 15 WPM with long gaps between letters, then shrink the gaps.
Where Morse still shows up
- Amateur radio: many licence holders still use it, because a narrow Morse signal can be heard when voice cannot.
- Navigation beacons: some radio beacons identify themselves with a short Morse code.
- Accessibility: some people with limited mobility can type using two switches and Morse.
- Phones and watches: a vibration or light flash can send a message when you cannot speak.
The idea of giving the shortest codes to the most common symbols is exactly what compression formats do. For a related story about encoding text, read about Base64, and for another simple cipher you can crack by counting letters, see the Caesar cipher.
Questions people ask
What does SOS mean in Morse code?
SOS is ... --- .... It is a distress signal chosen because the pattern is simple and unmistakable. It does not stand for any words.
How long is a dash compared with a dot?
Three times as long. The gap between signs of one letter is one dot, between letters three dots and between words seven dots.
Why is E just one dot?
E is the most common letter in English, so it was given the shortest possible code. T, the second most common, gets the single dash.
How do you write numbers in Morse code?
Every digit is five signs long: 1 is .----, 2 is ..---, 3 is ...--, 4 is ....-, 5 is ....., 6 is -...., 7 is --..., 8 is ---.., 9 is ----. and 0 is -----.
How fast can people send Morse code?
Beginners start at 5 to 10 words per minute. Experienced operators send 20 to 30, and top competitors reach well over 40.
Is Morse code still used?
Yes, mainly by amateur radio operators, in some navigation beacons and as an accessibility input method.