NATO Phonetic Alphabet Translator (Alfa, Bravo, Charlie…)

Understanding the NATO phonetic alphabet translator — concept and principle

This translator spells out letters and digits with the ICAO/NATO phonetic alphabet (Alfa, Bravo, Charlie …) so that names, codes and numbers can be passed clearly by phone or radio. It is used by pilots, call-centre staff, travellers spelling a booking code and anyone reading out an email address.

Letters to code words: with the default inputs the result is Kilo India Mike / Four… (3 letters, 4 digits).

How it is calculated

Each letter A–Z is replaced by its code word: A = Alfa, B = Bravo … Z = Zulu. Upper and lower case are treated the same.
Each digit becomes a number word (Zero, One …), or the ICAO radio form (Ze-ro, Wun, Too, Tree, Fow-er, Fife, Six, Sev-en, Ait, Nin-er).
A space between words is shown as "/".
Accented letters, Hangul and punctuation are kept as typed.

The principle

Many letters sound alike over a poor line: B, D, E, P, T and V are easy to confuse. The spelling alphabet replaces each with a distinct word chosen to be recognisable to speakers of many languages. ICAO spells Alfa and Juliett this way on purpose, so that French and other speakers pronounce them correctly. The radio forms of numbers, such as TREE and NIN-ER, make 3 and 9 harder to confuse with other words. The same alphabet is used by NATO, the ITU and many organisations.

Worked example

Default inputs: "Kim 4021", digits as words.

K = Kilo, I = India, M = Mike.
The space becomes /.
4 = Four, 0 = Zero, 2 = Two, 1 = One.
Result: Kilo India Mike / Four Zero Two One; 3 letters, 4 digits, 0 other characters.

How to read the result

Read each code word clearly, with a short pause between words and a longer one at "/". When spelling an email address, say "at" and "dot" in plain words. For names, say the name first, then spell it: "Kim, Kilo India Mike".

Common mistakes

Making up words ("A as in apple"), which the listener may not expect.
Spelling "Alpha" and "Juliet"; ICAO uses Alfa and Juliett.
Saying "oh" for zero, which can be confused with the letter O.
Spelling too fast for the listener to write down.

Keep in mind: Aviation and maritime radio procedures have additional rules for numbers, callsigns and phrasing. Follow the procedures that apply to your service.

Frequently asked questions

What is the NATO phonetic alphabet?

The ICAO radiotelephony spelling alphabet, A = Alfa to Z = Zulu, also used by NATO and the ITU.

Why is it spelled Alfa and not Alpha?

ICAO chose spellings that speakers of other languages pronounce correctly.

How do I say numbers on the radio?

ICAO uses forms such as TREE for 3, FIFE for 5 and NIN-ER for 9.

Sources: ICAO Annex 10, Volume II (Communication Procedures), §5.2.1.3 and Figure 5-1 (spelling alphabet), §5.2.1.4 (numbers)

Checked 9 Nov 2026. ICAO Annex 10 to the Convention on International Civil Aviation, Volume II (Communication Procedures), §5.2.1.3 and Figure 5-1 (radiotelephony spelling alphabet and pronunciation) and §5.2.1.4 (transmission of numbers); the same alphabet is used by NATO and the ITU.

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