Decode Morse Without Spaces
Spacing is part of the code. Remove it and the same marks become a puzzle.
By MorseCoder Team · Last updated: October 22, 2026
Typed Morse on MorseCoder expects spaces between letters and a slash between words. That mirrors how learners write code on paper. On the air, skilled operators still pause between letters, but recordings sometimes arrive as one continuous tone run. When gaps disappear, decoding becomes ambiguous: multiple letter chains can produce identical dot-dash streams.
A decoder cannot know which split you intended without extra context (language, call sign format, known phrase). The honest approach is to rank possible readings. Our Morse code decoder does that when you paste unspaced input.
Why ...---... is not always “SOS”
Visually, SOS is three dots, three dashes, three dots. Without enforced letter gaps, the stream might also be read as shorter letters stitched together, depending where you imagine breaks. Distress traffic works because everyone drills the same prosign rhythm and context. In exam or puzzle settings, always state which splitting rule you used.
Five worked ambiguity examples
-
...---...— Classic SOS rhythm, but the same run can split into shorter letters if you insert different gaps. -
.-— Could be A alone or E followed by T if you break after the first dot. -
-.— Often N, yet a long first dah plus a late dot might have been T then E with a missing letter gap. -
...— Three dits are S when grouped; three separate E letters if you triple the letter spacing. -
--..--— Could be Z (--..) plus an extra dash, or other multi-letter paths depending where you cut.
Frequency-aware decoders score splits using letter commonness in English. That helps pick SOS for ...---... in general text, but a callsign or grid square might favor a different path. Always treat ranked lists as hypotheses.
How to split by hand
Start from the left. Try the longest valid ITU symbol that fits, then recurse. When two paths remain, write both. Compare with audio: reinsert gaps where the sender paused. Use the timing page to remember that letter gaps are three units—often audible even when typists omit spaces.
For practice, encode a short word on the translator, remove spaces, and attempt recovery on the decoder page. Repeat with Farnsworth audio so your ear learns where letters end before you rely on software.
Try it: spaced vs unspaced
CW Radio: sine tone on HF. Telegraph: click sounder. Farnsworth: full-speed character shapes with spaced gaps for ear training.
Paste unspaced Morse in the Morse box on the decoder page for possible readings. Processing stays in your browser.