Colon in Morse code
Written “:”, in the ITU standard
The colon (:) in Morse code is ---..., said dah-dah-dah-di-di-dit: three dashes and then three dots, like O and S run together. It is part of the international standard, which names it the colon or division sign. The digit 8 is the same signal with one dot fewer, so the last dot decides which one you heard.
---... (dash dash dash dot dot dot)
“dah-dah-dah-di-di-dit”dash dash dash dot dot dot
6 elements · 3 dots, 3 dashes · 17 units
Hear it at your speed (WPM)
1133 ms at 18 WPM
The colon at a glance
- Morse code
- ---...
- Said as
- dah-dah-dah-di-di-dit
- Elements
- 6
- Length
- 17 units
- At 18 WPM
- 1133 ms
- ITU standard
- Yes
- Sounds like
- OSLetters run together
Colon or division sign
ITU-R M.1677-1 lists ---... among its punctuation marks as the colon or division sign. The same list calls the slash the fraction bar or division sign, so two signals can stand for ÷. In ordinary text the colon does the job it does in writing, before a list, a time or an explanation.
Three long, three short: hearing it
The colon is one of the easiest six-element marks to picture: O, ---, flowing straight into S, ..., with no letter gap. Think "OS": every long sound first, then every short one.
It takes 17 units, about 1.13 seconds at 18 WPM.
Hear it
- O---
- S...
The digit 8 plus one dot
- The digit 8 is
---.., the colon without its last dot. - The digit 7,
--..., is the colon with one dash fewer. - With a normal letter gap,
--- ...is two letters, O and S.
A colon whose final dot is clipped is copied as 8, which matters most in times, where both turn up next to figures.
Hear it
- 8---..
- 7--...
- OS--- ...
Sending a time like 5:30
Send the figures and the colon as separate characters with normal letter gaps. 5:30 is ..... ---... ...-- -----, four characters and 67 units, about 4.5 seconds at 18 WPM. It is the time in this page's practice box, so you can play it there.
Hear it
- 5:30..... ---... ...-- -----
Characters to compare
Close to the colon in sound, so the likeliest mix-ups.
- Colon minus its last dot: 8, dash dash dash dot dot
- The first half: O, dash dash dash
- The other division sign: Slash, dash dot dot dash dot
- Semicolon in Morse code: Semicolon, dash dot dash dot dash dot
- Two elements from Colon: 6, dash dot dot dot dot
- Two elements from Colon: 9, dash dash dash dash dot
Which one did you hear?
Listen, then pick or type the one you heard.
Try the colon in a word
Tap the colon yourself
Press for a dot, hold for a dash. Space works too.
- Send
- ---...
- Yours
- Nothing yet
Questions about Colon.
Is there a Morse code for punctuation?
Yes. The ITU standard gives the colon its own signal along with the period, comma, question mark and the other common marks. The Morse code punctuation chart shows every one of them and plays them.
Should I send ÷ as a colon or a slash?
Either is correct, since ITU-R M.1677-1 names both signals a division sign. The slash is also the fraction bar, as in 3/4, so in a message with fractions the colon keeps the two jobs apart.
Did American Morse have a colon?
Yes, but a different one. Wikipedia's table of American (Railroad) Morse writes it as KEE, a code unrelated to the International colon, so a Railroad colon does not decode with today's table. The American Morse code guide compares the two.
What is the history of Morse code?
It grew out of the electric telegraph that Samuel Morse and Alfred Vail developed in the late 1830s, and was first used on a public line in 1844. The history of Morse code follows it from there to the international code used today.