Morse Code Converter

Morse code: its encoding rules and timing standard

It is not a fixed-length code

Morse code represents characters with two signals (a short dot and a long dash), but each character uses a different number of signals. The letter E is a single dot and T is a single dash, while digits are uniformly 5 signals and most punctuation is 6.

The design follows the same idea as Huffman coding: the more frequent a letter is in English, the shorter its encoding. E, T, A, I and N are 1-2 signals, while Q, Y and Z are 4. This keeps the average length of a message as short as possible.

The timing standard (ITU-R M.1677)

Morse is about duration ratios, not absolute speed. Taking the length of one dot as 1 unit:

So ...---... is SOS with no spaces between characters, while ... --- ... is written with the word boundaries shown. The receiving operator tells characters from words purely by the gap length — get the gaps wrong and the same signal string decodes to completely different content.

Why ambiguity appears

Without the inter-character spaces, a string of dots and dashes is not uniquely decodable. For example, .... can be H (four dots), or EEEE, or IE, or SI, depending on where you split. Real telegraphy removes that ambiguity with strict timing (or explicit separators).

This is also the caution for plain-text conversion: the encoding must emit separators, or decoding cannot guarantee recovery. Some tools separate characters with a space and words with /; others use a single space between characters and three spaces between words. Agree on the convention before exchanging data.

Where it still shows up

• Amateur radio. Callsign identification and weak-signal (QRP) communication still treat Morse as one of the most efficient modes, because a narrow band carries farther at the same power.
• Aviation navigation. VOR and NDB stations continuously broadcast their three-letter identifier in Morse, so a pilot can confirm they are tuned to the right station — a simple, effective guard against dialing in the wrong frequency.
• Light signals and emergencies. SOS (...---...) is written into conventions as an international distress signal because it needs no equipment at all: a flashlight, a mirror or a whistle can send it.
• Nostalgia and learning. It survives in hobby use and as a vivid example of variable-length encoding.

The tool converts text and Morse in both directions, with an optional character separator (space or /), is case-insensitive, and runs entirely in your browser.