How To Use The Soundex

How To Use The Soundex


Instructions for using the Soundex coding system for surnames.

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Instructions for Using Soundex Codes

    Soundex is an alpha-numeric code of surnames based on how the surname sounds in English, thus eliminating, in part, the need to think about all the different ways a name could be spelled. Soundexes are used in American censuses between 1880 and 1920, and in other sources such as the Soundex Index to Naturalization Petitions Filed in Federal, State and Local Courts in New York, NY, including New York, Kings, Queens and Richmond Counties, 1792-1906, which is available at (see image to right). The need for understanding how to use Soundex has diminished with the advent of online censuses which you can search by the exact name spelling or similar (soundex) spelling. However, researchers must still know Soundex and how to translate a name into a code in order to use other data sources. Researchers can access other web sites which will automatically translate the surname of interest into a soundex code, or they can use the following steps to do it themselves.

    1. Retain the first letter of the name.

    2. Remove all occurrences of the following letters (unless it is the first letter): a, e, i, o, u, w, y and h.

    3. Assign number to the remaining letters, after the first letter, as follows:

    • b, f, p, v = 1

    • c, g, j, k, q, s, x, z = 2

    • d, t = 3

    • l = 4

    • m, n = 5

    • r = 6

    4. If two or more letters with the same number are adjacent in the original name (before step 1), or adjacent except for any intervening h and w (American censuses only), then omit all but the first.

    5. Return the first four characters (first letter plus three numbers; replace blank spaces with zeros).

    For example, the surname Acret is coded as follows:

    1. Retain the first letter - A

    2. Remove all occurrences of e and i, giving us Acrt

    3. Since c is 2, the name becomes A(c=2), (r=6), and (t=3) or A263. Eliminate any remaining letters (there are none in this example but would be in a longer name) since they are not needed; only the first letter and three numbers are required.

    Once you have determined the soundex code for the surname, given names are arranged alphabetically within the code. For example, you might find Adams = A352, then Abigail, Adam, Alphonso, Amy, etc., followed by A353, Abigail, Adam, Alphonso, Amy etc.

    The success of Soundex depends entirely on the accuracy of the first letter in the surname. If the name is read incorrectly, you will not likely be able to locate the person of interest. Here are some common errors indexers might make. The cursive capital letter K may be mistaken for an R. I once searched for a Knox family and couldn't figure out why none of them appeared in a census when I knew for an absolute fact that they were there. By pure luck I found them soundexed under R520! Cursive S and cursive L may also be mistaken for each other, as can F and T. And if you've ever wondered why there are so many people with the middle initial O, see if their surname is Reilly or Sullivan! Patrick OReilly is often indexed as Reilly, Patrick O! The same thing goes for names beginning with M or Mc. If the online index is available to search by given name only, and it is an unusual given name, sometimes it is easier to search by that rather than the surname.

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