Morse code is a timing system. Dots and dashes show the sound, but the silence between them is what keeps characters and words understandable.
The spacing rule is often summarized as 1–3–7. One unit separates parts of the same character, three units separate complete characters and seven units separate words.
Those gaps do different jobs. If they collapse into one generic pause, a receiver can no longer tell which marks belong together.
Start with one unit
At a given words-per-minute setting, one dot lasts one unit. A dash lasts three units.
- Gap between parts of one character: 1 unit
- Gap between characters: 3 units
- Gap between words: 7 units
The translator calculates one unit with the common 1200 / WPM relationship. At 20 WPM, a dot lasts about 60 milliseconds. A dash lasts about 180 milliseconds, a character gap lasts about 180 milliseconds and a word gap lasts about 420 milliseconds.
At 12 WPM, one unit lasts 100 milliseconds. The same pattern then uses a 100-millisecond dot, a 300-millisecond dash, a 300-millisecond character gap and a 700-millisecond word gap. Slowing the setting changes the duration of every unit, but it does not change their proportions.
| Speed | 1-unit dot | 3-unit dash or character gap | 7-unit word gap |
|---|---|---|---|
| 12 WPM | 100 ms | 300 ms | 700 ms |
| 20 WPM | 60 ms | 180 ms | 420 ms |
These numbers describe ideal scheduling. Speakers, headphones, browser timing and human sending can add small practical differences. The relationship between the gaps matters more than reading a stopwatch while listening.
The gap inside a character
A character such as A is written .-. The dot and dash are separate sounds, but the one-unit silence between them keeps both marks inside a single character rhythm. It is shorter than the silence that follows the finished A.
That internal gap is not normally written as a visible separator. The marks stay together in one code group. If you write . - with a normal character space, a decoder can interpret it as E followed by T instead of A.
Compare these two forms:
A
.-
E T
. -The marks are identical. Only the boundary changes. This is why spacing is part of the information rather than decoration around the information.
The gap between characters
After a complete character, the signal stays quiet for three units before the next character starts. On screen, this translator represents that character boundary with one normal space.
For SOS, the three groups are easy to see:
S O S
... --- ...The printed space does not mean the audio is silent for one unit. It is a compact written separator. During playback, the scheduler applies the full three-unit character gap.
An important implementation detail is that the final mark already ends with no extra semantic gap. The scheduler inserts the required boundary before the next character. It should not add a one-unit internal gap and then another complete three-unit character gap, because that would stretch the boundary beyond the intended timing.
The gap between words
A word boundary uses seven units of silence. It must be noticeably longer than the three-unit character gap. That contrast lets the listener group characters into words without seeing a slash.
The written translator uses / for this boundary:
SOS HELP
... --- ... / .... . .-.. .--.Spaces may appear around the slash for readability. The slash itself is the meaningful word separator. When you paste Morse into the tool, keeping that separator explicit gives the decoder a reliable place to restore a normal text space.
Why the written result uses spaces and slashes
On screen, each encoded character is separated by one normal space. Words are separated by /. For example:
SOS HELP
... --- ... / .... . .-.. .--.The single visible space does not mean one timing unit between characters. During playback, the tool schedules the full three-unit letter gap and seven-unit word gap.
This form is practical for copying because dots and dashes stay grouped by character. It also avoids depending on the exact visual width of multiple spaces, which can collapse in HTML, messaging apps or proportional fonts.
Some references show wider spaces between words, and some operators transcribe spacing in other ways. Before decoding pasted material, identify which convention the source uses. In this tool, a slash is the canonical word boundary and a normal space is the canonical character boundary.
Decode by boundaries before guessing letters
When you receive written Morse, split the message at word separators first. Then split each word into character groups. Only after the boundaries are clear should you look up the marks inside each group.
For this input:
.... .. / - .... . .-. .the slash creates two words. The first word has .... and .., which decode to H and I. The second has five groups, which decode to THERE. Working from boundaries prevents the marks near the slash from being attached to the wrong character.
If a group is not in the supported International Morse dataset, keep it in place as an unknown sequence. Do not silently remove it and join the surrounding letters, because that changes the apparent message and hides the location that needs correction.
A common decoding mistake
If every gap is treated the same, ... --- ... can become a stream of marks with no reliable character boundaries. Keep word gaps clearly longer than letter gaps, and letter gaps clearly longer than gaps inside a character.
Another mistake is adding visible spaces between every dot and dash. The input . . . contains three character groups and decodes as EEE. The input ... contains one group and decodes as S. A space is therefore not a harmless formatting choice inside this written convention.
A third mistake is using a slash between every character. A slash creates a word boundary, so ... / --- / ... reads as three one-letter words rather than SOS as one word. Use a normal space for the character boundary and reserve the slash for actual word separation.
Check spacing with sound and text
Use the Morse Code Translator to compare both forms of a short example. Enter SOS TEST in the Text panel and confirm that the Morse result contains spaces between the seven characters and one slash between the two words.
Select the Learn 12 preset and play the result. Listen for three levels:
- the brief one-unit silence connecting marks inside a character;
- the longer three-unit silence after a complete character;
- the longest seven-unit silence between SOS and TEST.
Play the same message at a higher speed. Every duration becomes shorter, but the three levels should remain distinguishable. If the written groups are correct but the message sounds crowded, return to a slower setting and listen for the word gap first.
A five-minute spacing exercise
Start with E T and compare it with A. E followed by T has a three-unit character gap between the dot and dash. A has a one-unit internal gap between the same two marks. This pair isolates the boundary without requiring a long message.
Next compare I M with U. The first form is .. -- with a character boundary in the middle. U is ..-, one character whose three marks remain connected by short internal gaps.
Finish with two short words such as HI THERE. Type them as text, inspect the slash, then play the result twice. On the second pass, write only the moments when you hear a character or word boundary. Compare those marks with the displayed groups.
Spacing becomes easier when you practice it as a hierarchy rather than a count: marks belong to a character, characters belong to a word and words belong to a message. The 1–3–7 rule gives each level a distinct amount of silence.
Use the complete Morse code alphabet when you need to confirm a character pattern, then return to the translator to hear it in context. Increase speed only after the character and word boundaries remain clear.