How many Q-codes are there?

There isn't a single small fixed set, there are dozens to over a hundred, depending on how you count.

The full design space is:

• QAA → QZZ
• That's 26 × 26 = 676 possible codes

… but only a fraction were ever assigned meaningful definitions. The system is, effectively, a large namespace, sparsely populated, heavily filtered by real-world use. While the system is large, the practical subset is small.

The structured reality

The Q-code system was standardized into three main groups:

1. Maritime / general radiotelegraphy (original set)

Developed by the British Post Office and later adopted internationally.

• ~100–150 codes were actually defined in early/ITU lists
• Of those:
  • Many are obsolete
  • Some are specialized (maritime, military, aviation)

Examples:

• QSL – I acknowledge receipt
• QTH – My location is …
• QRN – Natural static (noise)
• QRM – Man-made interference
• QSB – Signal fading

2. Aeronautical Q-codes

Used in aviation (many now replaced by plain language)

Examples:

• QNH – Altimeter setting (sea-level pressure)
• QFE – Field elevation pressure
• QNE – Standard pressure setting (1013.25 hPa)

3. Amateur radio subset

What hams actually use is a small working vocabulary, maybe ~20–40 are in common amateur use today.

Typical ham set:

• QSL, QTH, QRM, QRN, QSB
• QRZ (who is calling me?)
• QRP (low power)
• QRO (increase power)
• QSY (change frequency)
• QSO (contact)

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A structural detail worth appreciating

The Q-code system was cleverly designed so each code can have two meanings depending on context:

• A question
• An answer

Examples:

• QTH? → What is your location?
• QTH Los Angeles → My location is Los Angeles
• QSL? → "Did you receive my transmission?"
• QSL → "I confirm receipt."

That dual-use design:

• reduces transmission time
• avoids extra syntax
• works cleanly and saves time in Morse

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Is there a published list?

Yes, several authoritative ones. Search terms that work well:

• "ITU Q-code list PDF"
• "maritime Q codes table"
• "amateur radio Q signals list"

Official / historical sources

• ITU (International Telecommunication Union): the modern authority
• Originally: British Post Office / early wireless regulations

Various ranges within the Q-code system serve different purposes:

• QAA...QNZ: reserved for aeronautical services
  (ICAO Procedures for Air Navigation Services, Abbreviations and Codes (PANS-ABC) [Doc8400])
• QOA...QQZ: reserved for maritime services
  (ITU RR1990, Appendix 14)
• QRA...QUZ: for use by all services
  (ITU RR1990, Appendix 13, 14)
• QZA...QZZ: for other usage.

Here are the three most useful "tiers" of reference, depending on how deep you want to go, and some practical places you can actually browse:

1. Official / canonical Q-code lists in radio regulations (deep dive)

• International Telecommunication Union Radiocommunication Publications
  Alternatively, search the ITU site for "Q code appendix radio regulations"

The ITU maintains the formal definitions (historically in:

• Radio Regulations
• Appendix sections for Q-codes)

These are:

• Complete
• Dry
• "Sometimes" include codes you'll never see in practice

You will find:

• The ITU doesn't present Q-codes as a nice web page
• They live inside Radio Regulations / appendices / PDFs
• That’s why you won't find a clean "one page" link

2. Consolidated reference (best balance)

• Wikipedia

This is a surprisingly complete consolidated list useful since it:

• Combines maritime + aviation + amateur usage
• Groups codes logically
• Notes obsolete vs active usage
• Includes the origin story and historical context

For the "incessantly curious," this is probably your best first stop.

3. Ham-focused practical lists

• The ARRL Operating Aids page includes common ham Q-codes and gives you:

  • The working subset
  • Real-world meanings
  • Context of how operators actually use them

  If that link is broken, find the page's updated location by searching the ARRL site.

• Ralf D. Kloth's List of Q-codes includes a list ofcurrent Q-codes compiled from various sources.

Note that for long-term availability, many Web pages are preserved in the Internet Archive's Wayback Machine. If a link is unavailable, an archived version can usually be accessed there.

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Bottom line

There are hundreds of possible combinations, but:

• ~100–150 defined historically
• ~20–40 commonly used in ham radio

Full lists are published and accessible

The system is essentially an early protocol shorthand / compression scheme. At a system level, Q-codes behave a lot like:

• a compact command vocabulary
• with context-sensitive semantics
• over a noisy, low-bandwidth channel

… which is why they've survived for over a century.