How Morse Code Works
Morse code represents letters and numbers as sequences of dots (short signals) and dashes (long signals). The meaning comes from the pattern and the timing, not from the signal type.
Dots and dashes
A dot (dit) lasts 1 time unit. A dash (dah) lasts 3 time units, which is three times the length of a dot.
How Morse code works: the timing rules
- Gap between dots and dashes inside one letter: 1 unit
- Gap between letters: 3 units
- Gap between words: 7 units
These timing rules come from ITU-R M.1677-1, the international standard.
Example: SOS
SOS is ··· −−− ···. The three letters are sent as one continuous pattern, with no gaps between them, because it is a distress signal.
Speed (WPM) and the PARIS standard
Morse speed is measured in words per minute (WPM) using the word “PARIS,” which has 50 time units. At 20 WPM, one dot lasts 60 milliseconds and one dash lasts 180 milliseconds.
Try it
Use the translator to see how any text is converted to dots and dashes, and play it to hear the timing.
Why timing matters more than the signal
Understanding how Morse code works starts with timing. A dot and a dash are only different because of their length. The same sound played too short or too long can change the letter you hear. That is why Morse code is a timing system, not a set of symbols. Two operators can send the same message at different speeds, and a listener can still read it if the ratios stay correct: a dash is three times a dot, and each gap is a fixed number of units.
How speed is measured
Knowing how Morse code works also means knowing how speed is measured. Speed is written as words per minute (WPM), and the standard word used for the calculation is “PARIS.” PARIS has 50 time units including its gaps, so the speed is set by how long one unit lasts. At 20 WPM, one unit is about 60 milliseconds. That means a dot lasts about 60 milliseconds and a dash lasts about 180 milliseconds.
Farnsworth timing: full-speed characters with longer gaps
Farnsworth timing is a learning method that explains how Morse code works at a comfortable pace that keeps each character at full speed but adds extra silence between letters and words. The characters sound correct, which trains the ear to recognize them as complete rhythms, while the longer gaps give the brain time to think. Many beginners start with Farnsworth timing at 15 to 20 WPM, then turn it off once characters become automatic.
Common beginner mistakes when learning how Morse code works
- Dashes that are too short. A dash that is only twice as long as a dot is easy to confuse with two dots. Make dashes clearly three times as long.
- Gaps that are too short. Letters run together when the gap between letters is not longer than the gap inside a letter.
- Counting in your head. Learn to hear the rhythm of each letter rather than counting dots and dashes one by one.
- Going too fast too soon. Speed comes after accuracy. Practice slowly, then increase the speed in small steps.
How to start recognizing patterns by ear, step by step
Start with the letters that have very different rhythms, such as E (one dot), T (one dash), and I (two dots). Then move to letters with patterns that share a shape, such as S (three dots) and O (three dashes). Use the Morse code practice tools to repeat each letter until you recognize it without looking at the chart.
The rules described on this page come from the International Telecommunication Union recommendation ITU-R M.1677-1. Reading the standard alongside this guide shows exactly how Morse code works at every level of detail.
Frequently Asked Questions
How long is a dot in Morse code?
One time unit. At 20 WPM, that is about 60 milliseconds.
What is the gap between letters?
Three time units.
What is the gap between words?
Seven time units.
Related: Morse code alphabet, Morse code practice, SOS in Morse code, History of Morse code.