What is O in Morse code?

O in Morse code is "---", spoken dah-dah-dah. It is three elements long (dash dash dash) and takes 660 milliseconds to send at 20 words per minute. It sits three steps from the root of the Morse code tree.

Which Morse code characters are confused with O?

O (---) is easy to confuse with S (...), its mirror image with dots and dashes swapped, and with G (--.), K (-.-) and W (.--), each of which differs from it by a single element. Practise them back to back until the difference is a sound rather than a count.

How do you learn O in Morse code?

By its sound, not its shape: O is spoken dah-dah-dah. Listen to it at full speed instead of counting its elements. MorseForge's 7-day plan teaches it on day 4, together with D, K and G.

Reference plate · Letter 15 of 26

O in Morse code

O in Morse code is "---": three dashes, spoken "dah-dah-dah". It is one of the 8 three-element letters, so it sits three steps from the root of the Morse code tree, and it is the mirror image of S, which is dot-dot-dot. The 7-day plan teaches O on day 4. At 20 words per minute it takes 660 milliseconds to send.

Letter O3 elements

dah-dah-dah

Code: −−−
At 20 WPM: 660ms
Plan day: 4

O · dah-dah-dah

dash dash dash

~0.7s

Speed20 WPM

Practise O Send it on the key

O at a glance

Morse code: ---
Spoken: dah-dah-dah
Elements: 3: three dashes
At 20 WPM: 660 ms
At 5 WPM: 2640 ms
Morse tree: 3 steps from the root, below M
Mirror image: S
One element away: G, K and W
7-day plan: Day 4, with D, K and G
Koch order: 10 of 36

Where O sits in the Morse code tree

The path through the Morse code tree to O: from the root, a dash to T, a dash to M then a dash to O.

In the Morse code tree a dot branches left and a dash branches right, so every character sits exactly where its own code leads. O sits three steps from the root, directly below M. No letter hangs below O: it is a leaf of the tree.

See the whole Morse code tree

Characters confused with O

O is easiest to mistake for S, G, K or W. Practise them back to back until the difference is a sound rather than a count.

How to learn O

7-day plan

The plan teaches O on day 4, together with D, K and G. Learn it by its sound, "dah-dah-dah", at full speed rather than by counting its elements.

In the Koch method it is character 10 of 36.

Practise

Practice brings O back just before you would forget it, in all three skills: copying it by ear, reading it, and sending it yourself.

Guided lessons Practice

Words with O in them

Questions about O in Morse code

What is O in Morse code?: O in Morse code is "---", spoken dah-dah-dah. It is three elements long (dash dash dash) and takes 660 milliseconds to send at 20 words per minute. It sits three steps from the root of the Morse code tree.
Which Morse code characters are confused with O?: O (---) is easy to confuse with S (...), its mirror image with dots and dashes swapped, and with G (--.), K (-.-) and W (.--), each of which differs from it by a single element. Practise them back to back until the difference is a sound rather than a count.
How do you learn O in Morse code?: By its sound, not its shape: O is spoken dah-dah-dah. Listen to it at full speed instead of counting its elements. MorseForge's 7-day plan teaches it on day 4, together with D, K and G.

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