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Soundex Coding System

Soundex Coding System

The Soundex is a coded surname index based on the way a surname sounds rather than the way it is spelled.

Surnames that sound the same, but are spelled differently, like SMITH and SMYTH, have the same code and are filed together. The Soundex coding system was developed so that you can find a surname even though it may have been recorded under various spellings

To search for a particular surname, you must first work out its code. Every Soundex code consists of a letter and three numbers, such as W252. The first letter of the surname becomes the first letter of the soundex code. The numbers are assigned to the remaining letters of the surname according to the Soundex Coding Guide.

Soundex Coding Guide


Represents the letters


b, p, f, v


c, s, k, g, j, q, x, z


d, t




m, n



Disregard the letters: a, e, i, o, u, w, h, and y.

Step 1: Write the surname you are coding. Not counting the first letter, mark through all the vowels and the letters W, H, and Y.

Example: Smith. When you cross out the vowels and the "h", it looks like this: S m I t h

Step 2: Write the first letter and a dash.

Example: S-

Step 3: Now, write down the first three consonants after the first letter of the surname.If you don't have three consonants, don't worry about it. We'll do something in the last step to substitute.

Example: S-mt

Step 4: Substitute the appropriate numbers from the Soundex Coding Guide for the consonants.

Example: S-53

Step 5: Every Soundex number must be a 3-digit number, so add zeroes to make your code have three numbers.

Example: S-530

Special Rules:

  1. If the surname has double letters, they are treated as one letter. For example, Kell y codes as K400.
  2. A surname may have different letters side-by-side that have the same number on the Soundex Coding Guide. For example, Buerck codes as B620, and  oyd codes as L300.
  3. If a surname has a prefix, such as Van, Con, De, Di, La, or Le, code both with and without the prefix because it might be listed under either code. For example, vanDeusen may be found under V532 or D250.
  4. Mc and Mac are not considered prefixes.