Large capacitor have the value printed plainly on them, but smaller ones
often have just numbers printed.
The first two numbers are the 1^{st} and 2^{nd} significant
digits and the third is a multiplier code.
If there are only two numbers, these are read as Pico-Farads. An example: 47 printed on a small disk can be assumed to be 47 Pico-Farads.
The third digit tells how many zeros to write after the first two digits.
Digit Multipliers | |
third digit | multiplier (first two digits give the value in Pico-Farads) |
0 | 1 |
1 | 10 |
2 | 100 |
3 | 1,000 |
4 | 10,000 |
5 | 100,000 |
6 | not used |
7 | not used |
8 | .01 |
9 | .1 |
Example: A capacitor marked '124' is 12 with 4 more zeros or 120,000pF which is otherwise referred to as a .12 uF capacitor.
There is sometimes a tolerance code given by a single letter. Example: a 103J is a 10,000 pF with +/-5% tolerance.
Tolerance Code | |
letter | tolerance of capacitor |
B | +/- 0.10% |
C | +/- 0.25% |
D | +/- 0.5% |
E | +/- 0.5% |
F | +/- 1% |
G | +/- 2% |
H | +/- 3% |
J | +/- 5% |
K | +/- 10% |
M | +/- 20% |
N | +/- 0.05% |
P | +100% ,-0% |
Z | +80%, -20% |
There is also a 'letter-number-letter' code. For example, a labelled '224 Z5U' would represent a 220,000 pF capacitor with a low temperature rating of -10 deg C, a high temperature rating of +85 Deg C and a tolerance of +22%,-56%.
Dielectric Codes | |||||
First Letter | Low Temperature Requirement | Second Number | High Temperature Requirement | Third Letter | Max Capacitance Change over Temperature |
Z | +10 deg. C | 2 | +45 deg. C | A | +1.0% |
Y | -30 deg. C | 4 | +65 deg. C | B | +/- 1.5% |
X | -55 deg. C | 5 | +85 deg. C | C | +/- 2.2% |
6 | +105 deg. C | D | +/- 3.3% | ||
7 | +125 deg. C | E | +/- 4.7% | ||
F | +/- 7.5% | ||||
P | +/- 10.0% | ||||
R | +/- 15.0% | ||||
S | +/- 22.0% | ||||
T | +22%, -33% | ||||
U | +22%, -56% | ||||
V | +22%, -82% |