How do I read a guitar pot code?

The source-date code is six or seven digits. The first three are the maker (137 is CTS). In a seven-digit code the next two are the year and the last two the week; in a six-digit code one digit gives the year.

Why does a six-digit code give two possible years?

The one-digit year form was used from 1947 to 1959, so a 7 can mean 1947 or 1957. The guitar’s serial number or features usually settle which.

Does the pot date tell me when my guitar was made?

It tells you the earliest it could have been made, if the pots are original. Pots can sit in stock before use, and they are often replaced, so check all of them and compare with the serial number.

Guitar Pot Code Dater

Take the back plate or pickguard off and look at the volume and tone pots. Type the number stamped on one to see who made it and the week it was made. That’s the earliest the guitar can be, if the pots are original.

Pot maker codes

106 Allen-Bradley
134 Centralab
137 CTS (Chicago Telephone Supply)
140 Clarostat
304 Stackpole
381 Bourns Networks
615 IRC (International Resistance Company)

Questions

How do I read a guitar pot code?: The source-date code is six or seven digits. The first three are the maker (137 is CTS). In a seven-digit code the next two are the year and the last two the week; in a six-digit code one digit gives the year.
Why does a six-digit code give two possible years?: The one-digit year form was used from 1947 to 1959, so a 7 can mean 1947 or 1957. The guitar’s serial number or features usually settle which.
Does the pot date tell me when my guitar was made?: It tells you the earliest it could have been made, if the pots are original. Pots can sit in stock before use, and they are often replaced, so check all of them and compare with the serial number.

Sources

Blue Book of Electric Guitars, “Potentiometer coding: source date code”, checked 2026-11-12
Guitar HQ, “Dating vintage guitars and amps by source-date code”, checked 2026-11-12

Codes from other makers, and the letter-based codes some makers used later, aren’t in these charts, so the dater doesn’t guess at them.