The Official Morse Code Standard (ITU-R M.1677-1) Explained
International Morse code is defined by a short document from the International Telecommunication Union: Recommendation ITU-R M.1677-1. This page explains what that standard contains, including the rules almost nobody explains, such as how to send a percent sign, a fraction or a quotation, and what it leaves out.
What the Standard Is and Where It Came From
Morse code has had an international owner since 1865, when the first International Telegraph Conference in Paris founded the International Telegraph Union and adopted Morse code for international telegraphy. That body is today’s International Telecommunication Union (ITU), and it still publishes the reference definition of the code.
The current text is Recommendation ITU-R M.1677-1, “International Morse code”, approved on 3 October 2009. It says versions of the code have been in use since 1844, that it continues to be used mainly in the amateur and amateur-satellite services, and that it needs updating from time to time. It replaced the Morse part of an older telegraph recommendation, ITU-T F.1, which has been withdrawn.
The document is only a few pages long and free to download from the ITU. Its main part, an annex called “Operational provisions applying to Morse working”, is split into two parts: Part I defines the code itself, and Part II sets general rules for sending messages.
What the Standard Defines
| Section | What it covers | Where to go deeper |
|---|---|---|
| Part I, §1: Morse code signals | Every letter, figure, punctuation mark and service signal, with its dot-dash pattern | Alphabet, numbers, punctuation |
| Part I, §2: Spacing and length of the signals | The 1 : 3 : 7 timing ratios | Timing & WPM |
| Part I, §3: Signs with no Morse code | How to send ×, %, ‰, quotation marks, minutes and seconds | This page, below |
| Part I, §4: Groups, ordinals and fractions | How to send mixed letter-number groups, 25TH, and numbers like 1¾ | This page, below |
| Part II: General transmission rules | Calling another station, replying, waiting, separating and ending a message | This page, plus prosigns |
The Characters It Defines
The standard lists the 26 letters of the Latin alphabet, one accented letter (É), the figures 0 to 9, and 20 punctuation marks and service signals. The full letter chart is on the Morse code alphabet page and the common punctuation on the punctuation chart. A few entries surprise most people:
| Sign | Code | What the standard says |
|---|---|---|
| É (accented e) | ·· – ·· | The only accented letter in the international code |
| = (double hyphen) | – ··· – | Separates parts of a message; hams call it BT |
| + (cross) | · – · – · | Addition sign, and the signal that ends a telegram; hams call it AR |
| × (multiplication) | – ·· – | Sent as the letter X |
| @ (commercial at) | · – – · – · | Included for e-mail addresses |
| Understood | ··· – · | Service signal: message understood |
| Error | ········ | Eight dots: the last word was sent wrong |
| Wait | · – ··· | Service signal: please wait |
The Official Timing Rules
Section 2 of the standard is four sentences long, and every Morse translator and trainer depends on it:
- A dash is equal to three dots.
- The space between the signals forming the same letter is equal to one dot.
- The space between two letters is equal to three dots.
- The space between two words is equal to seven dots.
That is all the standard says about timing. It does not define a speed. Words per minute, the PARIS reference word and Farnsworth spacing are operating and training conventions built on top of these ratios; they are explained on the Morse code timing and WPM page.
How to Send Signs That Have No Morse Code
This is the part of the standard that almost no Morse reference explains. When a message contains a sign that has no code of its own, section 3 says how to send it:
| Sign | How the standard says to send it | Example |
|---|---|---|
| × (multiplication) | Send the letter X | 3 × 4 → 3X4 |
| % (percent) | Send 0, the fraction bar, then 0 | % → 0/0 |
| ‰ (per thousand) | Send 0, the fraction bar, then 00 | ‰ → 0/00 |
| A number with % or ‰ | Join the number to the sign with a single hyphen | 2% → 2-0/0, not 20/0 |
| A fraction with ‰ | Hyphens between each part | 4½‰ → 4-1/2-0/00 |
| “Quotation marks” | Send the quotation signal · – ·· – · before and after the words. Code converters may send the apostrophe twice instead | — |
| Minutes and seconds (′ ″) | Send the apostrophe · – – – – · once for minutes, twice for seconds; never the quotation signal | 1′15″ → 1, apostrophe, 15, apostrophe twice |
Why the hyphen matters: without it, “2%” sent as 2, then 0/0 would read as “20/0”. The hyphen is what tells the receiver where the number ends and the sign begins.
Numbers, Letters and Fractions Together
Section 4 covers mixed groups, which come up constantly in real messages:
- Figures and letters in one group are sent with no spaces between them, just as written.
- Ordinal numbers are sent as figures followed by letters: 25th becomes 25TH.
- A whole number with a fraction is joined to the fraction with a single hyphen: 1¾ is sent as 1-3/4, not 13/4, which would read as thirteen quarters.
The digits themselves, and why each one is exactly five signals long, are on the Morse code numbers page.
The Official Calling Procedure
Part II of the standard describes how two stations should start, run and end an exchange. Amateur operating practice grew out of these rules, which is why a modern CW contact still sounds like this:
- Calling: send the call sign of the station you want (no more than twice), the word DE, your own call sign, and K, the invitation to transmit. The call is always made at hand speed.
- Replying: the called station answers with the caller’s call sign, DE, its own call sign and K.
- Waiting: a station that cannot receive yet sends the wait signal · – ···. If the wait will be longer than ten minutes, it gives the reason and the likely duration.
- Separating: the double hyphen – ··· – separates the parts of a message, such as the address from the text, or the text from the signature.
- Ending a message: every telegram ends with the cross signal · – · – ·. The end of a transmission is the cross signal followed by K.
- Ending the contact: the station that sent the last message sends the end-of-work signal ··· – · –.
Radio amateurs know these signals by their letter names: the cross signal is AR, the double hyphen is BT, the wait signal is AS and end of work is SK. See Morse code prosigns for how they are used today and Morse code abbreviations & Q-codes for the shorthand that fills the rest of a contact.
What the Standard Does Not Cover
Much of what people assume is “official” Morse code is actually convention. The ITU standard does not include:
- The exclamation mark, semicolon and ampersand. They are common in charts and translators but are not in M.1677-1. The ampersand’s usual pattern, · – ···, is the ITU’s wait signal.
- A speed. Words per minute and the PARIS reference word are not defined in the standard.
- Training methods such as Koch or Farnsworth timing. See how to learn Morse code.
- Q-codes and most abbreviations. Those are in a separate ITU recommendation, M.1172.
- American Morse, the original telegraph code, which differs from the international code; see International vs. American Morse code.
- Non-Latin alphabets such as Cyrillic, Greek or Japanese Wabun code.
QuickMorse’s alphabet, numbers, punctuation and prosign pages are checked against this standard, and they point out where a common character is a convention rather than part of it.
Frequently Asked Questions
Who decides the official Morse code?
The International Telecommunication Union (ITU). Its Radiocommunication Sector publishes Recommendation ITU-R M.1677-1, “International Morse code”, which defines the characters, their timing and the basic transmission rules.
What is ITU-R M.1677-1?
It is the ITU recommendation that defines International Morse code. The current version was approved in October 2009. It covers the letters, figures and punctuation, the 1 : 3 : 7 timing, how to send signs that have no Morse code, and general rules for calling and ending a transmission.
Is the @ sign part of Morse code?
Yes. The ITU standard includes the commercial at sign, @, as · – – · – ·, so e-mail addresses can be sent in Morse code.
How do you send a percent sign in Morse code?
There is no Morse code for %. The standard says to send the figure 0, the fraction bar and 0 (0/0), joined to the number by a hyphen: 2% is sent as 2-0/0.
Is the exclamation mark part of International Morse code?
No. The exclamation mark, semicolon and ampersand are not in ITU-R M.1677-1. They are widely used conventions, but not every operator or tool supports them.
What is the official timing of Morse code?
A dash is three dots long. The gap between signals inside a letter is one dot, between letters three dots, and between words seven dots. The standard does not set a speed.
Explore More
Sources
- International Telecommunication Union, Recommendation ITU-R M.1677-1: International Morse code (PDF): characters, spacing, signs without a code, fractions and transmission rules.
- International Telecommunication Union, M.1677: International Morse code (record page): approval date of the current version.
- International Telecommunication Union, The 1865 International Telegraph Conference: the founding of the ITU and adoption of Morse code for international telegraphy.
- International Telecommunication Union, Recommendation ITU-R M.1172 (PDF): the separate list of Q-codes and abbreviations.
Sources last checked: September 26, 2026.