What is a single dot in morse code?

A single dot is the letter E. It is one dit, the short signal, which makes E the shortest character in ITU-R M.1677-1, the international standard. At 20 words per minute (WPM) that dit lasts 60 milliseconds.

One dit, played on its own. Drop the speed to 5 WPM and the same single mark lasts 240 milliseconds.

Why E is a single dit

ITU-R M.1677-1 gives every letter, digit and punctuation mark its own run of dits and dahs. E gets the shortest run there is: one dit, and nothing else. Only T is as short, and T is one dah.

Length is the whole difference between the two. A dit is one unit of sound and a dah is three, so E and T are each a single mark but T takes three times as long to send. That ratio is fixed by the standard, which is why the drawing above shows a circle one unit wide rather than a printed full stop.

How long a single dot lasts

Speed in morse is measured on the word PARIS, which is exactly 50 units long from the first mark to the end of the gap that follows it. One unit is therefore 1,200 milliseconds divided by the speed in words per minute (WPM):

5 WPM: a dit lasts 240 milliseconds
10 WPM: 120 milliseconds
20 WPM: 60 milliseconds

Press Play above and change the speed to hear the same single mark at each length. Nothing about the pattern changes, only the clock.

What turns a dot into a letter

A character ends when the silence after it is long enough. Inside one character the marks are one unit apart. Between characters the gap is three units, and between words it is seven. So a dit followed by three units of silence is E; a dit followed by one unit of silence and another dit is I, which is two dits.

Keep adding dits inside the same character and you climb a short ladder that is worth learning in one go:

E is one dit
I is two
S is three
H is four
the digit 5 is five

Past five there is nothing. No character in the standard is six or more dits long, so a longer run of dots is either more than one letter or a mistake in whatever you are reading.

If you are decoding a string

People usually arrive at this question holding a line of dots and dashes they want turned back into words. Counting marks by hand is slow and the gaps are easy to lose in a copied message, so paste the whole thing into the morse code translator instead and read the text straight off. The printable morse code chart has the full table on one sheet if you would rather work through it yourself.

Questions people ask next

What letter is a single dot in morse code?

E. No other letter, digit or punctuation mark in the international standard is a single dit.

What does a single dot represent in morse code?

One unit of sound, the shortest signal morse uses. On its own, followed by a gap of three units, it is the letter E.

What is the shortest letter in morse code?

E and T, at one mark each. E is a single dit and T is a single dah, and because a dah is three units long, T takes three times as long to send.

How long does a single dot last?

One unit, which is 1,200 milliseconds divided by the speed in words per minute. That is 240 milliseconds at 5 WPM, 120 at 10 WPM and 60 at 20 WPM.

What is one dot and one dash in morse code?

The letter A, sent as a dit, a one-unit gap, then a dah. Reversed, a dah then a dit, it is N.

Sources

Codes and timing follow Recommendation ITU-R M.1677-1 (10/2009), International Morse code (International Telecommunication Union, 2009).