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Phonetic Encoder (Soundex / Metaphone)

Encode a word or name to its Soundex code so similar-sounding names collide, with an optional Metaphone view for a second phonetic algorithm.

About this tool

The Phonetic Encoder turns a word or name into a phonetic code so that names that sound alike map to the same value — the trick behind fuzzy name matching, genealogy searches, and de-duplicating spelling variants. The default is American Soundex, a four-character code: it keeps the first letter, then maps the remaining consonants to digits (B,F,P,V→1; C,G,J,K,Q,S,X,Z→2; D,T→3; L→4; M,N→5; R→6) while vowels and H, W, Y map to 0.

The algorithm follows the classic rules exactly. Runs of the same digit that are adjacent, or separated only by H or W, collapse into a single digit, while letters separated by a vowel are encoded separately. All zeros are dropped, the retained first letter is prefixed, and the result is the first three digits right-padded with zeros to length four. This is why Robert and Rupert both encode to R163, and Ashcraft encodes to A261.

Switch the algorithm toggle to Metaphone (or ‘Both’) for a second, more modern phonetic view. Metaphone applies English pronunciation rules — silent-letter dropping, PH→F, TH→0 (theta), SH/TIA/SIO→X, soft versus hard C and G, and so on — producing a variable-length key that often groups homophones more accurately than Soundex for English words. Everything is a deterministic state machine computed locally in your browser; no data is looked up or transmitted.

Frequently asked questions

How does the Soundex encoding work?
Keep the first letter, then code the rest: B,F,P,V→1; C,G,J,K,Q,S,X,Z→2; D,T→3; L→4; M,N→5; R→6; vowels and H,W,Y→0. Collapse repeated digits (including those separated only by H or W), drop zeros, prefix the first letter, and pad or trim to four characters, e.g. Robert→R163.
Why do Robert and Rupert give the same code?
Both start with R and their consonant sequences map to the same digits (b/p→1, r→6, t→3), yielding R163. That collision is the whole point of Soundex: names that sound similar share a code, which is ideal for searching records with inconsistent spelling.
What is Metaphone and how is it different?
Metaphone is a later phonetic algorithm that applies English pronunciation rules rather than a fixed digit table. It handles silent letters, PH→F, TH→0, soft/hard C and G, and more, producing a variable-length key that often matches English homophones more precisely than Soundex.
Does it work on full names or phrases?
Both algorithms encode a single word — non-letter characters are stripped and the word is upper-cased first. For a full name, encode each part (first, last) separately. Everything is computed locally with no external lookup.

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