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Soundex & Metaphone Calculator

Encode names phonetically with American Soundex, Refined Soundex, NYSIIS and Metaphone, and compare two names side by side for a sound-alike verdict.

Phonetic codes

Type a name to see its American Soundex, Refined Soundex, NYSIIS and Metaphone codes. Add a second name to check whether the two sound alike.

What is the Soundex & Metaphone Calculator?

Phonetic algorithms turn a name into a code that reflects how it sounds rather than how it is spelled, so that Robert and Rupert both encode to R163 and can be matched despite the different letters.

  • Four algorithms at once: American Soundex, Refined Soundex, NYSIIS and Metaphone
  • Side-by-side comparison of two names with a per-algorithm match column
  • Overall verdict from how many algorithms agree
  • Multi-word names are encoded word by word
  • Optional full-length NYSIIS key instead of the standard 6-character form
  • Runs entirely in your browser; names are never uploaded

How to use the Soundex & Metaphone Calculator

  1. 1

    Type a name into the first box to see all four phonetic codes.

  2. 2

    Type a second name into the compare box to check whether the two sound alike.

  3. 3

    Read the per-algorithm Match column and the overall verdict above the table.

  4. 4

    Untick “Truncate NYSIIS to 6 characters” if you want the full-length NYSIIS key.

  5. 5

    Press “Copy codes” to take the results with you.

About the Soundex & Metaphone Calculator

Phonetic algorithms turn a name into a code that reflects how it sounds rather than how it is spelled, so that Robert and Rupert both encode to R163 and can be matched despite the different letters. They are the backbone of genealogy search, census indexing and duplicate detection in customer databases.

This calculator runs four published algorithms side by side. American Soundex is the US census standard: an initial letter plus three digits, with H and W acting as bridges. Refined Soundex uses a finer code table and no length limit. NYSIIS is the New York State system, producing a letter-only key. Metaphone applies English pronunciation rules, writing “0” for the TH sound.

Enter a second name and every algorithm is compared, giving you a per-algorithm match and an overall verdict. Different algorithms disagree by design — that disagreement is informative, not a bug. Everything runs in your browser, so names you paste are never uploaded.

Frequently asked questions

What is the Soundex code for Robert?

R163. The first letter is kept, then B gives 1, R gives 6 and T gives 3, with the vowels ignored. Rupert produces the same R163, which is exactly what Soundex is designed to do.

How does the Soundex algorithm work?

It keeps the first letter, maps the remaining consonants to digits 1 to 6 by sound group, drops vowels, collapses adjacent identical codes, then pads or truncates to four characters. H and W are skipped without separating two identical codes, which is why Ashcraft encodes to A261.

Which is better, Soundex or Metaphone?

Metaphone is generally more accurate for English because it applies real pronunciation rules rather than a fixed letter-to-digit table, so it handles combinations like PH, GH and TCH properly. Soundex is simpler, far older, and still the format many genealogy and government indexes are built on.

Why do the four algorithms disagree about my two names?

Because they encode different things. Soundex is coarse and groups many names together, Metaphone is stricter about actual pronunciation, and NYSIIS applies its own prefix and suffix rules. Agreement across several algorithms is stronger evidence of a match than any one of them alone.

What does the 0 in a Metaphone code mean?

It stands for the TH sound, the voiceless dental fricative that linguists write as theta. Metaphone has no letter for it, so Thomas encodes as 0MS. It is the digit zero, not the letter O.

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