Using it
Type the code printed on the capacitor: three digits such as 104, a code with a tolerance letter such as 473J, or a letter-for-decimal-point code such as 4n7 or 4R7. The output is the value in its handiest unit, and the rows give it in pF, nF and µF.
Swap the boxes to go from a value to its code. Type it with its unit, such as 100nF, 0.1uF or 22pF.
Reading the three digits
The first two digits are the value and the third is how many zeros to add, always in picofarads. 104 is 10 followed by four zeros: 100,000 pF, which is 100 nF or 0.1 µF. 473 is 47,000 pF, or 47 nF. 220 is 22 pF. Most charts also read a third digit of 9 as × 0.1 and 8 as × 0.01, for values below 10 pF.
Small values are often printed the other way, with a letter where the decimal point goes: 4R7 or 4p7 is 4.7 pF, 4n7 is 4.7 nF and 4u7 is 4.7 µF. This is the RKM code from IEC 60062, the same standard that covers resistor markings.
Tolerance letters (IEC 60062)
| Letter | Over 10 pF | Under 10 pF |
|---|---|---|
| B | ±0.1 pF | |
| C | ±0.25 pF | |
| D | ±0.5 pF | |
| F | ±1% | ±1 pF |
| G | ±2% | ±2 pF |
| J | ±5% | |
| K | ±10% | |
| M | ±20% | |
| S | −20% / +50% | |
| Z | −20% / +80% |
Common codes
| Code | pF | nF | µF |
|---|---|---|---|
| 101 | 100 | 0.1 | 0.0001 |
| 221 | 220 | 0.22 | 0.00022 |
| 471 | 470 | 0.47 | 0.00047 |
| 102 | 1,000 | 1 | 0.001 |
| 222 | 2,200 | 2.2 | 0.0022 |
| 472 | 4,700 | 4.7 | 0.0047 |
| 103 | 10,000 | 10 | 0.01 |
| 223 | 22,000 | 22 | 0.022 |
| 473 | 47,000 | 47 | 0.047 |
| 104 | 100,000 | 100 | 0.1 |
| 224 | 220,000 | 220 | 0.22 |
| 474 | 470,000 | 470 | 0.47 |
| 105 | 1,000,000 | 1000 | 1 |
Questions
What is a 104 capacitor?
100 nF, also written 0.1 µF or 100,000 pF.
What does the J in 104J mean?
The tolerance: J is ±5%. K is ±10% and M is ±20%.
What does 2A or 1H before the code mean?
That is usually a voltage rating code, which varies by maker; check the datasheet.
Sources
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