O in Morse Code

What Does O Look Like in Morse Code?

O has 3 signals (3 dashes) and takes 11 timing units to send. O is the longest all-dash letter. Only the numbers 1, 9 and 0 contain a longer run of dashes. See it next to every other letter on the Morse code alphabet chart.

Words That Start With O in Morse Code

Each word starts with ---. A space separates the letters. Type any other word into the Morse code translator to hear it.

Letters Easily Confused With O

T, M and O are one, two and three dashes. The number 0 is five dashes, so in a message with digits, listen for the length of the run. For a step-by-step method, read how to identify a letter from its Morse pattern.

How Long Does O Take to Send?

O is 11 units long: 3 for each of the three dashes and 1 for each of the two gaps between them. A dot is 1 unit and a dash is 3. The Morse code timing guide explains how speed changes the length of a unit.

How Efficient Is O in Morse Code?

Alfred Vail gave common letters short codes after estimating how often each letter is used. Comparing O’s share of English text with the length of its code shows how well that plan worked for this letter.

O is where the design breaks down. It is the fourth most common letter in English, yet its three dashes take 11 units, as long as rare letters like X and Z. The older American Morse sent O as two dots with a gap, which was far shorter. International Morse chose three dashes for clarity on noisy radio and cable circuits, accepting the extra length.

Some languages add accented forms of O that are not in the English alphabet. Apart from É, these are national extensions rather than part of the ITU standard, so an English-only decoder may show them as unknown characters.

Frequently Asked Questions