The system works like this: Letters with similar sounds have the same code (see the key at right). The code begins with the first letter of the surname. Of the remaining letters, cross out all vowels (a, e, i, o and u) plus w, h and y. With the consonants, form a three-digit code. For Carpenter, the code begins with C. Cross out a, e, e, and code r as 6, p as 1, n as 5. Disregard the remaining letters. The code is C615.
Code as one digit any double letters, such as tt or rr (Saddler S346), or consonants with the same code that occur together, such as ck or sc (Scanlon S545). Names with h or w between same-code letters are coded as if the h or w was not in the name at all (Sachse S200, not S220). If you run out of key letters before you have the required three digits, simply add zeros (Mott M300; Lee L000). Names with the same code appear together in the Soundex.
To account for different surname spellings and mistranscriptions, you should code the usual surname variations to use in your Soundex search. Be aware that some names and their common variations have different Soundex codes because of subtle spelling changes, such as Larson (L625) and Lawson (L250), or Mood (M300) misread as Wood (W300). When you determine the codes for your family, you’re ready to get the Soundex microfilm for the census year, their state and their code. After you record the county, enumeration district, page and line number for the family’s census listing from the Soundex card, you can go to the census schedule.
If you’re using online databases, you may be able to search on a Soundex code, or a database might give you a Soundex option that automatically generates the code and looks for matches.
The Soundex Key
|b p f v||1|
|2||c s k g j q x z|
|no code||a e i o u h w y|