Our commitment: Every Morse code character on this site has been verified against ITU-R M.1677-1 — the official International Telecommunication Union Morse Code standard. We cross-reference with ARRL and LCWO. Errors are fixed within 24 hours of a verified report. Report corrections to hello@onlinemorsecode.com.
Primary Source: ITU-R M.1677-1
All Morse code on OnlineMorseCode follows ITU Recommendation M.1677-1 (International Morse Code) — the global official standard maintained by the International Telecommunication Union, updated most recently in 2009. This document defines:
- The exact dot-dash pattern for every character (A–Z, 0–9, punctuation)
- The precise timing ratios for all signal elements
- Regional extensions for Arabic, Hebrew, Cyrillic, Spanish, French, and other languages
The ITU standard is used by amateur radio operators, maritime communicators, aviation navigation beacons, military signals units, and accessibility technology developers worldwide.
How the Character Mapping Was Verified
ITU-R M.1677-1 primary source
Every character mapping is taken directly from the ITU document tables. We do not rely on third-party sources as a primary reference — the ITU document is the authoritative source.
ARRL cross-reference
The American Radio Relay League (ARRL) publishes Morse code tables used by hundreds of thousands of licensed operators. All Latin-alphabet characters are cross-checked against ARRL tables.
LCWO verification
LCWO (Learn CW Online) is the largest online platform for Morse code learning, used by the ARRL and leading ham radio educators. Our character set is checked for consistency with LCWO's implementation.
Audio verified by licensed CW operators
The audio output timing has been listened to and confirmed by licensed amateur radio operators with CW experience. Operators who use Morse code daily can identify timing errors by ear that might not be visible in code.
User correction process
Any user can submit a correction at hello@onlinemorsecode.com. Every report is reviewed, verified against ITU-R M.1677-1, and corrected within 24 hours if confirmed. We log all corrections transparently.
ITU Timing Standard — Exact Specifications
We implement all five ITU timing ratios correctly using the Web Audio API. The base unit is the dot duration, calculated from the target WPM:
| Element | Duration | Example at 15 WPM | Notes |
|---|---|---|---|
| Dot (·) | 1 unit | 80ms | Base time unit |
| Dash (−) | 3 units | 240ms | Exactly 3× the dot |
| Inter-element gap | 1 unit | 80ms | Between dots/dashes within a letter |
| Inter-letter gap | 3 units | 240ms | Between separate characters |
| Inter-word gap | 7 units | 560ms | Between words |
Speed is measured using the standard PARIS method (50 units per word). 1 WPM = sending the word PARIS once per minute. This matches the ARRL and ITU standard definition.
Farnsworth Timing
Our Farnsworth implementation sends each character at the target character speed while extending only the inter-letter and inter-word gaps. This is the standard Farnsworth method as described by Don Andrews (W6TTB) and implemented by LCWO and the G4FON Koch trainer. Character-level timing is never slowed — only the spaces between characters are extended.
Language Extension Sources
| Language | Source | Characters covered |
|---|---|---|
| Arabic | ITU-R M.1677-1 Arabic extension | All 28 base letters |
| Hebrew | ITU Hebrew Morse extension | All 22 Aleph-Bet letters |
| Cyrillic / Russian | ITU-R M.1677-1 Cyrillic extension | All 32 Russian letters |
| Spanish | ITU Spanish extension (Ñ, accents) | A–Z + Ñ, Á, É, Í, Ó, Ú |
| French | ITU French extension | A–Z + É, È, À, Â, Ê, Î, Ô, Û, Ç, Ù |
| Filipino / Indonesian | Standard Latin ITU Morse (A–Z) | Full Latin alphabet |
| Hindi (Devanagari) | Established amateur radio practice | Major vowels and consonants |
Comparison with Official ITU Source
The ITU-R M.1677-1 recommendation is publicly available from the ITU website. The full document defines the character mappings we use. If you wish to verify any character on this site against the official source, download ITU-R M.1677-1 from itu.int and compare the tables directly.
Where our implementation differs from any other online Morse tool, we follow the ITU document. If you believe we have made an error in interpreting the standard, we welcome that report at hello@onlinemorsecode.com — we will review the ITU document and correct any genuine discrepancy.
Error Reporting Process
Report an error: Send the page URL, the character in question, and what you believe the correct code should be to hello@onlinemorsecode.com. Every report is reviewed against ITU-R M.1677-1 within 24 hours. If confirmed, the error is fixed immediately and the correction is logged. We do not ignore correction reports.
Last full review: March 26, 2026 · Next scheduled review: June 2026