Capacitor Coding
Small value ceramic, mylar, and polyester type capacitors have their values stamped on their
bodies as a numerical code, 102, 473, etc. in very small print. These codes can easily be
deciphered into a standard value in microfarads.
The first two digits of the code indicate the two significant digits of the value. The third digit is
the number of zeros to the right. Writing the first two digits, then the zeros will yield the value in
picofarads. If desired, that value can now be converted to microfarads by moving the decimal
point six places to the left.
Example 1:
You have a capacitor with "103" stamped on it.
The first two digits are: 1 0
The third digit is: 3 so add three zeros to the 1 0 --> 1 0, 0 0 0 pf
Now to covert the 10,000pf to microfarads:
Move the decimal point to the left six places giving 0.01 microfarads.
Example 2:
You have another capacitor with "104" stamped on it.
The first two digits are: 1 0
The third digit is: 4 so add four zeros to the 1 0 --> 1 0 0, 0 0 0 pf
Now to covert the 100,000pf to microfarads:
Move the decimal point to the left six places giving 0.10 microfarads.
Values greater than 1 microfarad are also coded this way.
Example 3:
Number stamped on capacitor: 223
Decoded value: 22 + 000 = 22,000pF = 0.022 microfarads
Below is a table showing standard codes for different tolerances:
These letter codes are usually stamped on the capacitor next to or below the value.
C = +/- 0.25pF
M = +/- 20%
D = +/- 0.5pF
P = +100 - 0%
J = +/- 5%
Y = -20 +50%
K = +/- 10%
Z = -20 + 80%