Capacitor Number Codes
Capacitors often have a marking or code printed on them used to indicate their value. Large capacitors are able to have their values marked on the case, but on smaller ones there is insufficient space to give the data and capacitor code systems are required. Some use a colour code, but increasingly capacitors used a figure code is used on the smaller capacitors.
Table of common ceramic capacitor markings:
| Capacitor Code | Capacitor Value |
|---|---|
| 10 | 10 pf |
| 22 | 22 pf |
| 47 | 47 pf |
| 101 or 100 | 100 pf |
| 221 or 220 | 220 pf |
| 471 or 470 | 470 pf |
| 102 | 1 nf |
| 222 | 2.2 nf |
| 472 | 4.7 nf |
| 103 | 10 nf |
| 223 | 22 nf |
| 473 | 47 nf |
| 104 | 100 nf |
| 224 | 220 nf |
How to calculate the capacitance
On a large electrolytic capacitor there is sufficient space to mark the value, the tolerance, working voltage, and often other data such as the ripple voltage. Smaller capacitors may only have room for a few figures printed as a code for the value.
On one scheme there may just be two figures. These refer to the capacitance in picofarads, i.e. 10 is 10 pF.
Another scheme uses three or four characters. It bears many similarities to the colour code system adopted for resistors, but without the colour part of the coding scheme. The first two figures refer to the significant figures, whereas the third one acts as a multiplier. The value of the capacitor being denoted in picofarads.
Multiplier used on Capacitor Marking Code
| Last Figure (3rd or 4th) | Multiplier |
|---|---|
| 0 | 1 |
| 1 | 10 |
| 2 | 100 |
| 3 | 1000 |
| 4 | 10000 |
| 5 | 100000 |
The fourth character provides the tolerance figure for the component. A variety of codes are available to describe the tolerances. The tolerances denoted by the characters P and Z are normally used by electrolytic or tantalum capacitors.
| Tolerance lookup table | |
|---|---|
| Character | Tolerance |
| C | 0.25pf |
| D | 0.5pf |
| F | 1% |
| G | 2% |
| J | 5% |
| K | 10% |
| M | 20% |
It can be seen from the tables that a capacitor with the marking 104J has a value of 100 000 pF and has a tolerance of +/- 5%.
In some instances there may also be a voltage rating. This is printed as a figure suffixed with the letter V after it. This is unlikely to be included on smaller components where there is insufficient space to include it.