International Morse Code — Complete Reference Guide
The official International Morse Code standard (ITU-R M.1677-1) — every letter, number, prosign, and punctuation mark, plus the timing rules and symbol meanings behind them. Use the Morse Code Translator to convert any text instantly.
What Does ___ Mean in Morse Code?
Quick answers for the most-searched Morse code patterns — each one links to the full alphabet chart further down the page.
| Pattern | Meaning |
|---|---|
| .- | The letter A |
| .. | The letter I (two short dots) |
| ... | The letter S (three short dots — three dashes make O, so SOS is ... --- ...) |
| --- | The letter O (three long dashes) |
| ..-. | The letter F (dot-dot-dash-dot, or di-di-dah-dit) |
| .... | The letter H (four short dots) |
| - | The letter T (a single dash — the shortest possible dash code) |
| . | The letter E (a single dot — the shortest possible Morse code) |
| ...---... | SOS — the international distress signal (S-O-S) |
| / | A word space separator in written Morse notation |
Don't see what you're looking for? Paste any Morse pattern into the Morse Code Translator to decode it instantly.
What Is International Morse Code?
International Morse Code is a universal communication standard in which every letter, digit, and common punctuation mark is represented by a unique sequence of short signals (dots) and long signals (dashes). Developed in the 1830s by Samuel Morse and Alfred Vail for use with the electric telegraph, the system was standardized internationally in 1851 so that operators in any country could exchange messages using the same patterns — regardless of language or national origin.
The version recognized worldwide today is defined by the International Telecommunication Union (ITU) in recommendation ITU-R M.1677-1. Every character mapping and timing rule on this page — and in every tool on this site — comes from that standard.
Is Morse code universal?
Yes. International Morse Code is a universal standard — the same character mappings are used by amateur radio operators, aviation systems, and maritime signaling worldwide. A message sent from Pakistan can be decoded by any trained operator in Japan, Brazil, or the United States using the same chart.
Dit and Dah — Why Operators Don't Say Dot and Dash
Morse code has only two signals. In writing they're shown as a dot (.) and a dash (—), but operators — and any serious learner — call them dit and dah instead. That isn't just convention; it's practical. "Dit" is a crisp, short syllable that sounds like the actual short tone. "Dah" is drawn out, matching the longer tone you actually hear. Learning to think "di-dah" (A) rather than "dot-dash" lets your brain process Morse code as rhythm and sound, rather than mentally converting written symbols first — which is exactly what fast operators do.
// Standard timing: everything is measured in units
Dit (dot) = 1 unit
Dah (dash) = 3 units
Gap within letter = 1 unit
Gap between letters = 3 units
Gap between words = 7 units
International Morse Code Alphabet (A–Z)
The full 26-letter alphabet, mapped to International Morse Code. Each pattern is the globally recognized ITU standard.
A
.-
B
-...
C
-.-.
D
-..
E
.
F
..-.
G
--.
H
....
I
..
J
.---
K
-.-
L
.-..
M
--
N
-.
O
---
P
.--.
Q
--.-
R
.-.
S
...
T
-
U
..-
V
...-
W
.--
X
-..-
Y
-.--
Z
--..
Morse Code Numbers (0–9)
Unlike the alphabet, Morse code numbers follow a clear, learnable pattern — which is why experienced operators often memorize them in a single session.
The number pattern rule:
Every digit is exactly 5 symbols long. From 1 to 5, you add one dot at a time, replacing a dash:
- 1 → .----
- 2 → ..---
- 3 → ...--
- 4 → ....-
- 5 → .....
After 5, the pattern reverses — one more dash is added back with each step: 6 is -...., 7 is --..., 8 is ---.. and so on until 0, which is all five dashes (-----). A quick mnemonic: after 5, the number of dashes equals the digit minus 5.
0
-----
1
.----
2
..---
3
...--
4
.....-
5
.....
6
-....
7
--...
8
---..
9
----.
Punctuation in International Morse Code
| Symbol | Morse Code | Notes |
|---|---|---|
| . | .-.-.- | Period / full stop |
| , | --..-- | Comma |
| ? | ..--.. | Question mark |
| / | -..-. | Slash (also used as word-space symbol in written Morse) |
| = | -...- | Equals sign / double dash |
Prosigns — Procedural Signals
Prosigns are special Morse sequences sent as a single unit (without the normal letter gap between characters) to control the flow of radio communication — not to spell a word. They're written in brackets to distinguish them from regular letter combinations.
| Prosign | Morse | Meaning |
|---|---|---|
| AR | .-.-. | End of message |
| SK | ...-.- | End of contact / end of work |
| BT | -...- | Double dash / paragraph break |
| KN | -.--. | Invite specific station to transmit |
| K | -.- | Invitation to transmit (any station) |
| SOS | ...---... | International distress signal |
SOS in Morse Code — What It Means and Why That Pattern
... --- ...
S O S
SOS (... --- ...) is the international Morse code distress signal, adopted at the International Radiotelegraph Conference in 1906. Contrary to widespread belief, SOS doesn't stand for "Save Our Souls" or "Save Our Ship" — those backronyms came later. The pattern was chosen for a purely practical reason: three dots, three dashes, three dots is a perfectly symmetrical, unmistakable sequence that stands out clearly from ordinary traffic even on a noisy or fading signal.
In practice, the SOS prosign is sent as a single unbroken sequence without letter gaps — the full nine-symbol pattern is transmitted as one continuous group. It's also the only prosign most non-radio people can recognize by sight.
International vs. American Morse Code
International Morse Code (used today)
Standardized in 1851, uses only dots and dashes of two fixed lengths. Used by amateur radio, aviation, and maritime systems worldwide. This is the version on this page and in all tools on this site.
American Morse Code (historical)
Samuel Morse's original 1830s version for U.S. landline telegraph. Used variable-length dashes and internal gaps within some characters. Now obsolete outside of historical demonstrations.
Where International Morse Code Is Still Used
Amateur (Ham) Radio
CW (continuous wave) Morse operation is an active part of the hobby worldwide, with dedicated contests and frequency bands.
Aviation Navigation Beacons
VOR and NDB ground-based navigation aids still broadcast their identifier in International Morse Code for pilots to verify tuning.
Maritime Signaling
While replaced for routine use, SOS and other Morse signals remain recognized emergency methods for ships and coast guards.
Assistive Technology
People with limited mobility or speech can communicate using Morse input via a single switch, eye blinks, or breath puffs.
Frequently Asked Questions
What does .- mean in Morse code?▼
.- is the letter A — one dot followed by one dash.
What does .. mean in Morse code?▼
.. is the letter I — two short dots.
What does ... mean in Morse code?▼
... is the letter S — three short dots. Combined with three dashes and three more dots (... --- ...), it spells SOS.
What does ..-. mean in Morse code?▼
..-. is the letter F — two dots, one dash, one dot (di-di-dah-dit).
What does .... mean in Morse code?▼
.... is the letter H — four short dots.
What does ...---... mean in Morse code?▼
...---... is SOS — the international distress signal. Three dots for S, three dashes for O, three dots for S again.
What does / mean in Morse code?▼
A forward slash / represents the space between words in written Morse notation. In transmission it's a 7-unit silence.
Is Morse code a universal language?▼
Yes. International Morse Code is standardized globally by the ITU (ITU-R M.1677-1), so the same character mappings apply worldwide.
What is the difference between dit and dah?▼
A dit is the short signal (dot), lasting 1 unit. A dah is the long signal (dash), lasting 3 units. Operators use these spoken terms because they match the actual sounds transmitted, which helps build faster recognition than counting dots and dashes.
How do numbers work in International Morse Code?▼
Every digit 0–9 is exactly 5 symbols long. From 1 to 5, dots replace dashes one at a time. After 5, the pattern reverses and dashes replace dots one at a time up to 0, which is five dashes.