What is the Metaphone Code System?

Metaphone, a phonetic algorithm, was invented by Lawrence Philips and first described in Computer Language magazine. It’s like the Soundex system discussed in this blog but an advanced technique of the concept.

Metaphone is used for indexing words by their English pronunciation. It’s an improvement of the Soundex algorithm by using information about variations and inconsistencies in English spelling and pronunciation to produce a more accurate encoding. This helps to match words and names that sound similar.

Like the previously discussed with the Soundex system, metaphone transforms words into codes based on phonetic properties. However, unlike Soundex which operates on a letter-by-letter scheme and returns a letter with three numbers, Metaphone analyzes both single consonants and groups of letters called diphthongs (TH, SH, CH, PH, WH) and returns what looks like the original word abbreviated.

How the Metaphone Code System Works

The Metaphone algorithm operates by first removing non-English letters and characters from the word being processed. Next, all vowels are removed unless the word begins with a vowel. If that’s the case, all vowels except the initial one are discarded. Finally, all consonants and groups of consonants are mapped to their Metaphone code. The rules for grouping consonants can be complicated.

Original Metaphone codes use the 16 consonant symbols 0, B, F, H, J, K, L, M, N, P, R, S, T, W, X and Y.

  • ‘O’ represents “TH”
  • ‘X’ represents “SH” or “CH”
  • The remaining letters represent their familiar English pronunciations.
  • Vowels A, E, I, O and U are also used but only if they appear at the beginning of the word.

Rules for Using the Metaphone Code:

  1. Drop duplicate adjacent letters, except for C
  2. If the word begins with ‘KN’, ‘GN’, ‘PN’, ‘AE’, ‘WR’, drop the first letter
  3. Drop ‘B’ if after a ‘M’ at the end of the word
  4. ‘C’ transforms to an ‘X’ if it’s followed by ‘IA’ or ‘H’ (unless it is part of ‘SCH’, in which case it transforms to ‘K’). ‘C’ transforms to ‘S’ if followed by ‘I’, ‘E’, or ‘Y’. Otherwise, ‘C’ transforms to ‘K’
  5. ‘D’ transforms to ‘J’ if followed by ‘GE’, ‘GY’, or ‘GI’. Otherwise, ‘D’ transforms to ‘T’
  6. Drop ‘G’ if followed by ‘H’ and ‘H’ is not at the end or before a vowel. Drop ‘G’ if followed by ‘N’ or ‘NED’ and is at the end
  7. ‘G’ transforms to ‘J’ if before ‘I’, ‘E’, or ‘Y’, and it is not in ‘GG’. Otherwise, ‘G’ transforms to ‘K’
  8. Drop ‘H’ if after the vowel and not before a vowel
  9. ‘CK’ transforms to ‘K’
  10. ‘PH’ transforms to ‘F’
  11. ‘Q’ transforms to ‘K’
  12. ‘S’ transforms to ‘X’ if followed by ‘H’, ‘IO’, or ‘IA’
  13. ‘T’ transforms to ‘X’ if followed by ‘IA’ or ‘IO’. ‘TH’ transforms to ‘0’. Drop ‘T’ if followed by ‘CH’
  14. ‘V’ transforms to ‘F’
  15. ‘WH’ transforms to ‘W’ if at the beginning. Drop ‘W’ if not followed by a vowel
  16. ‘X’ transforms to ‘S’ if at the beginning. Otherwise, ‘X’ transforms to ‘KS’
  17. Drop ‘Y’ if not followed by a vowel
  18. ‘Z’ transforms to ‘S’
  19. Drop all vowels unless it is the beginning of a word


Williamson: WLMSN. Other surnames that share this Metaphone code are Willemsen, Willemssen, Williamson, Wilmsen and Wulmsen
Schneider: SXNTR
Anderson: ANTRSN. Other surnames that share this Metaphone code are Aandriesen, Anderiessen, Anderisen, Anderissen, Anderriessen, and many more.

Try It Out! Are you interested to see what surnames would be coded to using the metaphone code system? Check out this tool from Genealogieonline.com.