Understanding the SOUNDEX code


The Soundex is a system begun during Franklin Roosevelt's presidency. His administration wanted to put many people to work in government programs. One of these programs was the WPA, which employed people to do many things for the government including organizing the Soundex.

These workers each took the census records, one county at a time, and wrote out a filing card for each household, naming all people listed in the census. Included on the card are: name, age, location, birthday and relationship to head of household for every person in every household. Not all information on the original census is given, but enough to identify the members of each household. Every surname was given a code (see Soundex code). These codes give numerical value to each letter of the alphabet.

The workers began with the 1900 census and listed each household in the entire United States on a separate file card. This system enables us to look at one surname in a whole state and find the exact locality of all persons in the state with that surname. Then we can go to the census records for that county, find the page listed in the Soundex and view all of the information collected by the census taker. No longer is it necessary to spend hours and hours looking at every entry, county by county to find the right entry.

Census records from 1880, 1900 and 1910 have been soundexed as of 1995. Others records will be processed in the future.


Soundex algorithms are methods by which one encodes the letters of a name to a alphanumeric code in order to store and retrieve similar-sounding names. For example, the names Castellano Kastelyano Chasteliano Qastelano might conceivably be names that were all spelled in the Castilian way at one time, but now have a variety of spellings because of the vagaries of different alphabets in various countries. Typically, the Russell Soundex code strips all vowels (except when the first letter of the name), and strips duplicate consonants: Castellano becomes CSTLN Next, similar phonemes are encoded with similar numbers. For example, M and N, both nasal letters, are encoded with the same digit. For instance, the Russell Soundex code for CSTLN is C234.

Double Letters

Any double letters side by side should be treated as one letter. For example HASSON is coded as if it were spelled HASON (H250). ALHADEFF is coded as if it were ALHADEF (A431).

Variations in spellings or misspellings should produce the same code number: BENSON = B525 BENSION = B525 BENZION = B525 BENCION = B525.

1 = B P F V
2 = C S K G J Q X Z
3 = D T
4 = L
5 = M N
6 = R




  1. Enter the surname for which to generate SOUNDEX code.
  2. Click on the SOUNDEX button.
  3. See the corresponding SOUNDEX code in the field.

Enter the surname to generate a SOUNDEX code:

The SOUNDEX code for this surname is:


Additional Rules for Understanding the Conversion

  • Disregard the letters A E I O U W Y H

  • If your name has a prefix like Van, Von, De, Di, Le or La - code it both with and without the prefix. It might be listed under either code. (Mc and Mac are not considered prefixes.)

  • If your surname has double letters, they should be treated as one letter. Example: Hasson. The second S should be slashed out. In the name Alhadeff, the second F should be slashed out.

  • Your surname may have different letters side-by-side which have the same coding number. Example: Hamner. (5 is the number for both M & N.) These letters should be treated as one letter and the N should be slashed out. Another example: Jackson. (2 is the number for C, K and S.) The K and S should be slashed. This rule applies when the letters are at the beginning of the surname, also. Example: Pfister. Both P and F are in the #1 category, therefore the letter F should be slashed out.

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