How is Metaphone better than Soundex?

Metaphone applies English pronunciation rules to letter groups (like silent GH or PH sounding as F) instead of a flat letter table. This produces fewer false matches than Soundex on English words.

What do the symbols 0 and X mean?

Metaphone uses 0 (zero) for the "th" sound and X for the "sh"/"ch" sound. The other symbols are ordinary consonants: B X S K J T F H L M N P R 0 W Y.

Are vowels kept in the key?

Vowels are kept only when they are the first letter of the word. After that, vowels are dropped, which is why "phone" encodes to FN.

Is this the original Metaphone or a variant?

This is the original 1990 Metaphone by Lawrence Philips. For ambiguous pronunciations, see the Double Metaphone tool, which returns a primary and an alternate key.

Does it work for any language?

No. Metaphone encodes English pronunciation rules, so names and words from other languages may encode poorly. Cologne Phonetics suits German and Caverphone suits New Zealand names.

Metaphone Encoder — Gera Tools

What this tool does

Metaphone is a phonetic algorithm by Lawrence Philips (1990) that produces a short key representing how an English word sounds. Unlike Soundex, which maps letters with a flat table, Metaphone applies English pronunciation rules to letter combinations, so it produces more accurate matches with fewer collisions. This encoder computes the key in your browser using the 16 standard Metaphone consonant symbols.

How it works

The algorithm first handles silent initial clusters: leading GN, KN, PN, WR and AE drop their first letter, initial X becomes S, and initial WH becomes W. It then walks the word left to right, emitting consonant symbols according to context. Key transformations include:

PH        -> F        (phone -> FN)
TH        -> 0        (think -> 0NK, where 0 is the "th" sound)
SH / -SIO -> X        (ship -> XP)
CH        -> X        (chair -> XR)
silent GH -> dropped  (night -> NT)
C before I/E/Y -> S; otherwise K

Vowels are retained only at the start of the word and dropped elsewhere, doubled consonants are collapsed, and the 16-symbol alphabet (B X S K J T F H L M N P R 0 W Y) keeps the key compact. The result is a phonetic fingerprint: differently spelled but similar-sounding words converge on the same key.

Example and notes

“Thompson” encodes to 0MPSN and “Tompson” to TMPSN — close but distinguished by the leading TH. “Knight” gives NT because the K and GH are silent. Use the key as a blocking or candidate-generation step in fuzzy search and deduplication, then confirm matches with edit distance or manual review. For names with genuinely ambiguous pronunciation, the Double Metaphone encoder returns two keys to widen recall. All processing is local.