How Morse Code Works

Morse code uses only two signal elements: a short signal called a dit (dot, ·) and a long signal called a dah (dash, —). The entire system relies on precise timing relationships between these elements. Per the ITU-R M.1677-1 standard, one dah lasts exactly three dit units, the gap inside a letter is one dit, between letters three dits, and between words seven dits.

The Timing Rules

Everything in Morse code is measured relative to the dot duration, the shortest unit. All other timings are multiples of this unit:

Example: Sending "HI"

Measuring Speed: Words Per Minute (WPM)

Morse code speed is measured in Words Per Minute (WPM). The standard reference word is PARIS, which contains exactly 50 dot-units when including all internal and word spacing.

This means at 20 WPM, the word PARIS is transmitted 20 times per minute, giving a dot duration of 60ms (1.2 seconds ÷ 20).

Frequency and Tone

When transmitted by radio, Morse code is sent as a continuous wave (CW) signal. The receiver produces an audible tone, typically between 400 Hz and 1000 Hz. Most operators prefer a tone around 600–700 Hz, which sits in a comfortable range for the human ear and cuts through background noise effectively.

Character Design Logic

Morse code was designed with efficiency in mind. The most frequently used letters in English have the shortest codes:

The ITU Standard

The International Telecommunication Union (ITU) maintains the official standard for International Morse Code under Recommendation ITU-R M.1677. This standard defines character assignments, timing rules, and operating procedures used globally.