What Is Morse Code?

Morse code has no fixed speed, only fixed proportions. All timing is measured in units, and a unit is the length of one dot. ITU-R M.1677-1 sets the spacing:

1. 1A dash lasts three units.
2. 2The gap between the dots and dashes inside a letter is one unit.
3. 3The gap between two letters is three units.
4. 4The gap between two words is seven units.

Here is MORSE CODE drawn to scale. Dashes are three times as long as dots, the narrow gaps sit inside letters, the wider ones between letters, and the widest one between the two words.

Sent this way, MORSE CODE is 89 units long, which takes 5.34 seconds at 20 words per minute.

Speed is measured in words per minute (WPM) with PARIS as the standard word. PARIS is 43 units, and with the 7-unit gap after it, exactly 50. Twenty of those a minute makes 1,000 units a minute, so each unit lasts 60 milliseconds. At any speed, one unit is 1,200 divided by the WPM, in milliseconds:

Because the code is just "on" and "off" in these proportions, anything that can be switched on and off can carry it: an electric current, a radio wave, a lamp or a tone.

Type your name or any message into the translator and press Play. It writes the dots and dashes as you type and plays them at true timing; switch on Light or Vibrate to see or feel the same signal. The full Morse code translator also has Farnsworth spacing for learners (wider gaps between letters sent at full speed), seven more code tables and an MP3 download.

On the radio, Morse usually arrives as a tone, so operators know it as sound. When radio receivers began turning the code into tones, operators started saying a dot as "dit" and a dash as "dah". A dot that is not the last part of a letter shortens to "di", so A is "di-dah" and L (.-..) is "di-dah-di-dit".

Here are a few common ones. CQ is the general call, "calling any station", that starts a radio contact.

• A

  .-5 units · 0.30 s

• N

  -.5 units · 0.30 s

• S

  ...5 units · 0.30 s

• O

  ---11 units · 0.66 s

• CQ

  -.-. --.-27 units · 1.62 s

Length is part of the sound. At 20 WPM, E lasts 0.06 seconds and T 0.18 seconds. A, N and S each take 0.30 seconds, while O, three dashes, takes 0.66 seconds.

• AA in Morse code
  .-
• BB in Morse code
  -...
• CC in Morse code
  -.-.
• DD in Morse code
  -..
• EE in Morse code
  .
• FF in Morse code
  ..-.
• GG in Morse code
  --.
• HH in Morse code
  ....
• II in Morse code
  ..
• JJ in Morse code
  .---
• KK in Morse code
  -.-
• LL in Morse code
  .-..
• MM in Morse code
  --
• NN in Morse code
  -.
• OO in Morse code
  ---
• PP in Morse code
  .--.
• QQ in Morse code
  --.-
• RR in Morse code
  .-.
• SS in Morse code
  ...
• TT in Morse code
  -
• UU in Morse code
  ..-
• VV in Morse code
  ...-
• WW in Morse code
  .--
• XX in Morse code
  -..-
• YY in Morse code
  -.--
• ZZ in Morse code
  --..
• 0Number 0 in Morse code
  -----
• 1Number 1 in Morse code
  .----
• 2Number 2 in Morse code
  ..---
• 3Number 3 in Morse code
  ...--
• 4Number 4 in Morse code
  ....-
• 5Number 5 in Morse code
  .....
• 6Number 6 in Morse code
  -....
• 7Number 7 in Morse code
  --...
• 8Number 8 in Morse code
  ---..
• 9Number 9 in Morse code
  ----.

The shortest codes went to the most common letters. Alfred Vail designed the first alphabetic code so that each letter's length was roughly the inverse of how often it appears in English text, which is why E, the most common letter, is a single dot. Later revisions moved a few codes, but many still follow that rule.

The full Morse code alphabet adds punctuation and accented letters, with sound for every character. To learn it by ear, see how to learn Morse code.

Samuel Morse and Alfred Vail. Morse's first code sent numbers that had to be looked up as words in a code book. Vail replaced it with a simpler alphabetic code, which made messages much quicker to read.

On 24 May 1844, Morse sent "What Hath God Wrought?" over his electromagnetic telegraph from Washington, DC, to Baltimore. Vail received it in Baltimore and sent the same message back to the Capitol.

• What hath God wrought (1844)

  .-- .... .- - / .... .- - .... / --. --- -.. / .-- .-. --- ..- --. .... -189 units · 11.34 s

That line used the original American code; the card above plays the message in today's International code, where it runs 189 units, or 11.34 seconds at 20 WPM. Modern Morse descends from a revision Friedrich Gerke made in 1848: he kept only two elements, the dot and the dash, and added codes for German umlauts and CH. For what happened next, from Gerke to radio, read the history of Morse code.

There are two main Morse codes for Latin letters, plus separate tables for other scripts.

• American (Railroad) Morse, the original landline code, has gaps inside some letters and dashes of more than one length. C, O, R, Y and Z have spaces inside them, L is a single long dash, and the digit 1 is .--., which International Morse uses for P. See American Morse code.
• International Morse uses one length of dot and one of dash, and no extra spaces inside letters. It is the ITU standard.

Languages written in Latin letters use the International table with a few extra letters. The ITU table itself includes É (..-..), and German sends Ä as .-.-, Ö as ---. and Ü as ..--. The accented letters page lists the rest.

Other scripts have tables of their own, so one signal means different letters: .- is A in International Morse, А in Russian, Α in Greek, א in Hebrew, ا in Arabic, イ in Japanese (Wabun) and ㅗ in Korean (SKATS). The Japanese Morse code guide covers Wabun. Chinese is sent as numbers: the Chinese telegraph code gives each character a four-digit number from 0000 to 9999.

It is still on the air in a few places:

• Amateur radio. ARRL's station W1AW sends Morse code practice from 5 to 35 WPM and code bulletins at 18 WPM, on nine frequencies.
• Aviation. Radio navigation beacons send their identifiers in Morse, and the FAA's pilot manual names a VOR beacon's Morse identifier, or its recorded voice ID, as the only sure way to identify it.
• The military. The US Navy still trains Manual Morse intercept operators at Corry Station in Pensacola, Florida: about 40 sailors a year, according to a 2016 Navy report. More in military Morse code.
• Accessibility. Google worked with Tania Finlayson, a Morse code assistive technology developer, to bring Morse typing to Gboard for iOS in July 2018, so you can enter text as dots and dashes.

Ships have left it behind. Under the Global Maritime Distress and Safety System (GMDSS), ships under the SOLAS safety convention had to fit satellite and radio distress equipment by 1 February 1999, a change that ended Morse code communication for all but a few users, such as radio amateurs. The ITU's standard says its use in the mobile and fixed radio services is shrinking. Is Morse code still used? goes through each use with its source.

To read Morse you hear, open the microphone decoder and hold your phone near the sound.

None of the three, though it gets called all of them.

• Not binary, in the computer sense. A computer's binary uses two symbols of the same length. Morse has two signal lengths (1 and 3 units) and three gap lengths (1, 3 and 7), and the gaps carry meaning: ... is S, but . . . is EEE.
• Not a cipher. A cipher hides a message from anyone without the key. The Morse table is published by the ITU for anyone to read.
• Not a language. It has no words of its own. It spells out the letters of a language, so English and French go through the same table. Is Morse code a language? explains the difference.

• The ITU still publishes the standard. Recommendation ITU-R M.1677-1 is dated October 2009 and notes that versions of the code have been in use since 1844.
• Eight dots, ........, is the signal for an error.
• The @ sign has a code, .--.-., in the ITU table.
• Sent as three letters, SOS is 27 units long: 1.62 seconds at 20 WPM. SOS in Morse code has the signal to play and flash.
• Since 23 February 2007, the FCC has not required a Morse code test for the General or Amateur Extra amateur radio licence.
• A VOR beacon under maintenance may send T-E-S-T (- . ... -) in place of its identifier.