Morse Code Encoder/Decoder, Text ⇄ Morse (Audio)

What this tool does

This page converts any text into International Morse Code (the dots and dashes defined by ITU-R M.1677-1) and decodes Morse back into text. It also plays the encoded message as audio using the Web Audio API so you can hear what real Morse sounds like, with adjustable speed from 5 to 30 words per minute. Five common prosigns (procedural signals: <SK>, <BK>, <AR>, <KN>, <CT>) are supported behind a toggle for ham-radio operators.

Morse code was invented by Samuel Morse and Alfred Vail in the 1830s-1840s as the encoding that turned the electric telegraph into a usable communication system. The original American Morse Code (1844) was replaced in international use by the Continental / International Morse Code (sometimes called "Continental Morse") standardized at the 1865 Paris Telegraph Conference and updated by the International Telecommunication Union (ITU) to its current form in the 1930s. The ITU-R M.1677-1 recommendation is the modern authority; it documents every letter (A-Z), every digit (0-9), the common punctuation, and the procedural prosigns used by amateur radio operators.

Today, Morse is used by amateur radio operators (who call it "CW" for "continuous wave"), maritime and aeronautical distress beacons, low-power experimental transmitters, and as an accessibility / cognitive-training tool. The SOS distress call (... --- ...) is still universally recognized even though it is technically just three letters with no special meaning; the choice is purely mnemonic because the pattern is unmistakable to listeners.

How to use this encoder/decoder

1. Type any text into the top input box. The Morse output appears immediately in the panel below. Letters are auto-uppercased; spaces between words become /.
2. Click "Copy Morse" to copy the encoded string to your clipboard. Paste it into a logging program, an email, or a QSO (amateur-radio contact) record.
3. Click "Play" to hear the message as audio. The playback uses a clean 800 Hz sine-wave tone (the standard Morse practice frequency) with proper dit/dah/gap timing per ITU-R M.1677-1.
4. Adjust the WPM slider (5-30 words per minute) to change speed. Beginners usually start at 5 WPM; experienced operators routinely copy at 25-30 WPM.
5. Switch the direction with the "Encode ⇄ Decode" toggle. In Decode mode, paste a Morse string (dots/dashes separated by spaces, / for word breaks) and the plain-text result appears below.
6. Toggle prosigns on/off if you are an amateur-radio operator and need to encode or decode <SK>, <BK>, <AR>, <KN>, <CT>. When prosigns are off, the angle-bracket characters are treated as plain text.

Algorithm, Mapping and timing

The encoding is a pure lookup: each character maps to its fixed symbol sequence per ITU-R M.1677-1. The standard alphabetic mapping (case-insensitive; lowercase auto-uppercases) is:

• E = ., T = - (the two one-symbol letters, the most common in English)
• A = .-, I = .., M = --, N = -., S = ..., O = ---
• D = -.., G = --., K = -.−, R = .-., U = ..-, W = .--
• B = -..., C = -.-., F = ..-., H = ...., J = .---, L = .-..
• P = .--., Q = --.-, V = ...-, X = -..-, Y = -.--, Z = --..
• 0 = -----, 1 = .----, ..., 9 = ----.

Common punctuation and special characters: . = .-.-.-, , = --..--, ? = ..--.., ' = .----., ! = -.-.--, / = -..-., ( = -.--., ) = -.--.-, & = .-..., : = ---..., ; = -.-.-., = = -...-, + = .-.-., - = -....-, _ = ..--.-, " = .-..-., $ = ...-..-, @ = .--.-.

A space between words is encoded as a single forward-slash / in the plain-text output, which corresponds to the 7-unit inter-word gap in the audio signal.

Timing (PARIS standard, ITU-R M.1677-1 §3)

Every Morse signal is built from a single unit duration, with these multipliers:

• dit (dot) = 1 unit
• dah (dash) = 3 units
• intra-character gap (between dits/dahs within a letter) = 1 unit
• inter-character gap (between letters within a word) = 3 units
• inter-word gap = 7 units

The "PARIS" standard fixes the WPM (words per minute) to 5 characters per word (PARIS = 50 units at the standard character length). One WPM equals 1.2 seconds per unit (1200 / WPM ms). At 15 WPM, one dit = 80 ms, one dah = 240 ms, inter-character = 240 ms, inter-word = 560 ms. The page's WPM slider implements this scaling: at 30 WPM every duration halves; at 5 WPM every duration doubles.

Prosigns

Prosigns (procedural signals) are multi-letter sequences run together without the normal inter-character gap. They are written in angle brackets: <SK> (Silent Key, end of contact), <BK> (Break), <AR> (End of message), <KN> (Go ahead, specific station), <CT> (Start of message / tune). When prosigns are enabled on this page, the encoder and decoder treat these as single symbols with the standard spacing.

Worked examples

1. Encode "SOS", the universal distress call

The most famous Morse sequence. S = ..., O = ---, S = .... With the standard inter-character gap (3 units) between letters: ... --- .... Three short, three long, three short, unmistakable to any trained listener. Audio: dit dit dit [gap] dah dah dah [gap] dit dit dit. The call is chosen because it is easy to remember, easy to send, and stands out rhythmically; it has no inherent meaning, just a memorable pattern.

2. Encode "HELLO"

H = ...., E = ., L = .-.., L = .-.., O = ---. Joined with inter-character gaps: .... . .-.. .-.. ---. This sequence is the canonical "first transmission" example in most amateur-radio licensing study guides.

3. Encode "PARIS" (the calibration word)

P = .--., A = .-, R = .-., I = .., S = .... With inter-character gaps: .--. .- .-. .. .... PARIS is exactly 50 unit durations including inter-character gaps, which is why it became the calibration standard for the words-per-minute metric: 1 word/minute = 50 units/minute = 1.2 seconds per unit.

4. Decode .... . .-.. .-.. ---

Reading each token: .... = H, . = E, .-.. = L, .-.. = L, --- = O → "HELLO".

5. Encode "CQ" (amateur-radio "calling any station")

C = -.-., Q = --.- → -.-. --.-. This is the universal ham-radio calling sequence: "CQ CQ CQ DE [your call] K" invites any station to respond.

6. Decode "... --- ..."

... = S, --- = O, ... = S → "SOS".

7. Edge case, lowercase auto-uppercase

Morse is uppercase-only by convention. Typing "hello world" produces "HELLO WORLD" and then encodes it to .... . .-.. .-.. --- / .-- --- .-. .-.. -... Some encoders preserve case by inserting a special prosign before lowercase letters; this encoder does not, by ITU convention.

8. Empty input

Decoding an empty string returns an empty string. The "Play" button on an empty message does nothing (no audio is generated).

Where Morse code shows up

• Amateur radio (ham CW), the dominant remaining use. CW (continuous-wave Morse) signals are detectable at signal-to-noise ratios where voice fails. Many hams worldwide enjoy CW as a deliberate, low-bandwidth operating mode.
• Maritime and aeronautical distress, while voice distress calls ("Mayday", "Pan-Pan") replaced Morse decades ago on most frequencies, the automatic SOS alert still appears in 500 kHz maritime beacons (mostly decommissioned but historically iconic) and in aviation VHF ELT (Emergency Locator Transmitter) beacons.
• Low-power experimental transmitters, QRP (low-power, under 5 watts) enthusiasts favor CW because Morse is intelligible at signal levels where voice is not.
• Accessibility and cognitive training, Morse has been studied as a cognitive training tool (the neural plasticity involved in learning the code) and as a low-bandwidth input method for people with motor impairments who can produce two distinct signals (tap / long tap) more reliably than full typing.
• Cryptographic puzzles and escape rooms, the visual novelty of dots and dashes makes Morse a common puzzle device.
• Historical telegraphy, re-enactors, museums, and the US National Scouting Museum teach Morse with working telegraph keys; the encoding remains a living link to the 19th-century electric telegraph.
• Film and theatre, the iconic "beep beep beep" sound of Morse is a universal audio shorthand for "transmission in progress," used in movies and TV whenever a radio operator is depicted.
• Bicycle, running, and aviation racing, some extreme-sport timing systems still transmit split times as short Morse bursts on pocketable low-power radios.

Common mistakes

• Wrong timing ratios. The dit:dah ratio is exactly 1:3, and the inter-character gap is exactly 3 units (3x a dit). Stretching the dah to 2 units and ignoring the gap makes the code unreadable. The audio playback on this page encodes the timing precisely; use it as the reference.
• Confusing prosigns with regular letters. <SK> and SK are different sequences, prosigns have the inter-character gap removed between letters, producing a "run-together" sound. The prosign toggle on this page distinguishes them.
• Treating space as "no character". A space in the input produces / in the Morse output (a 7-unit gap), which is essential for separating words. Skipping the gap makes "HELLO WORLD" indistinguishable from "HELLOWORLD".
• Pasting Morse with line breaks or extra spaces. Different encoders separate letters with single spaces, double spaces, or pipes (|). This decoder expects single spaces between elements of the same letter, single spaces between letters, and / between words.
• Trying to send mixed case. Morse is case-insensitive, a and A produce the same .-. Lowercase input is uppercased on encode.
• Confusing Morse with binary. Morse is variable-length (1 to 4 symbols per letter for the standard alphabet), unlike fixed-length binary encodings. Do not try to use Morse as a binary protocol.
• Speeding up too fast. Beginners copy at 5 WPM comfortably; expert operators reach 30-40 WPM. Jumping straight to 30 WPM is overwhelming; use the slider progressively.
• Forgetting ITU updates. ITU-R M.1677-1 is the modern authority; older references (e.g., the ARRL pre-1990 handbook) may list slightly different prosigns. The mapping table on this page follows the current ITU standard.

Frequently Asked Questions

What is the difference between American Morse and International Morse? American Morse (the original 1844 code, designed by Samuel Morse and Alfred Vail) was optimized for English letter frequency and had variable-length dashes. It was replaced in international use by the Continental / International Morse Code standardized at the 1865 Paris Telegraph Conference because American Morse could not represent non-English letters (notably accented characters) and required close tuning to a specific operator's timing habits. All modern amateur-radio, maritime, and aeronautical Morse uses International Morse.

Why is the international distress call "SOS" specifically? SOS (... --- ...) is memorable, distinctive, and easy to send, but it has no special "meaning" in Morse beyond three short, three long, three short. It was adopted in 1906 at the International Radiotelegraph Convention in Berlin as the universal maritime distress call, and the choice was mnemonic, not semantic. The earlier German distress call "CQD" (-.-. --.- -..) lost out to SOS because SOS is faster to send and easier to recognize.

What is the standard Morse tone frequency? Morse practice oscillators typically use 600 Hz to 800 Hz as the reference tone. The 800 Hz figure is standard in amateur-radio practice and is the frequency this page uses for audio playback. Real radio transmissions modulate this tone onto an RF carrier at the operating frequency (e.g., 14.025 MHz for the 20-meter CW band).

How are letters with diacritics handled (é, ñ, ö)? International Morse as standardized in ITU-R M.1677-1 covers the 26 unaccented Latin letters, digits, and common punctuation. Accented characters are not part of the standard. Amateur-radio operators typically transliterate accented characters to their unaccented equivalents (é → E) before encoding.

Can I send Morse faster than 30 WPM? Yes, experienced operators regularly send at 40-60 WPM, and competitive Morse copy (radio sport) goes beyond 100 WPM. Speeds above 30 WPM become a perceptual test more than a technical one; the operator's brain learns to hear whole words rather than individual letters. The page's slider caps at 30 WPM because above that, the audio's individual elements become too short for clean Web Audio API scheduling in a browser.

What is the Farnsworth method for learning Morse? Farnsworth spacing sends individual letters at a fixed character speed (e.g., 15 WPM) but widens the inter-character and inter-word gaps so the overall word rate is much lower (e.g., 5 WPM). This lets the learner hear correctly-spaced letters without yet being able to copy at full speed. The standard WPM metric on this page uses PARIS timing (inter-character = 3 units, inter-word = 7 units); switching to Farnsworth requires adjusting the gap ratios manually, which this page does not implement.

What does "73" mean in ham radio? 73 is amateur-radio shorthand for "best regards", it is operator slang, not Morse, but it is often transmitted in Morse as --... ...--. The number code for 73 is 7 = --..., 3 = ...--. The same convention applies to "88" ("love and kisses") = --.. ---...

Can this tool handle Arabic, Chinese, or Cyrillic Morse? The ITU standard Morse alphabet covers Latin letters, digits, and common punctuation only. Non-Latin scripts have their own Morse code systems (e.g., Russian Morse extends the Latin table with Cyrillic-specific sequences). This page focuses on the International Latin/Arabic-numeral Morse; non-Latin alphabets are out of scope.

Is Morse code still useful for non-ham operators? Yes for emergencies and accessibility. The cognitive-load advantages (low bandwidth, recognizable at low signal levels, two-signal input method) make it useful in niche contexts. But for general communication, modern digital modes (FT8, PSK31, MFSK) have replaced Morse as the standard low-bandwidth digital mode in amateur radio.

References

• ITU-R Recommendation M.1677-1 (2009). International Morse Code. International Telecommunication Union, Radiocommunication Sector. Defines every standard letter, digit, punctuation mark, and the procedural prosigns used in modern Morse.
• ARRL (American Radio Relay League). The ARRL Handbook for Radio Communications. Annual edition (latest: 2025). Chapter on CW operating procedures and Morse code history; standard practice guide for amateur-radio operators.
• ARRL. W1AW Code Practice Schedule and Morse Code Reference. Free downloadable PDF covering all standard prosigns and operating abbreviations used in amateur-radio Morse.
• Samuel F. B. Morse (1840). US Patent 1,647 / 1,648. Improvement in the Mode of Communicating Information by Signals by the Application of Electromagnetism. Original telegraph patent disclosing the encoding that became Morse code.
• International Radiotelegraph Convention (1906, Berlin). Convention Radiotélégraphique Internationale. Article XI adopted "SOS" as the universal maritime distress signal.
• Carron, L. (1986). Morse Code: The Essential Language. American Radio Relay League. ISBN 978-0872590353. Introductory text covering the alphabet, prosigns, and operating practices.
• Wells, D. (2009). The Sweep of Time: A History of Telecommunications in New Zealand from 1850 to 2000. Includes a chapter on the global standardization of Continental Morse at the 1865 Paris Conference and its adoption by British and Commonwealth telegraph services.