How to Interpret Capacitor Values
Reading capacitor values is typically straightforward, though it can become challenging for very small capacitors due to limited space for markings. Smaller capacitors often display a numeric code consisting of three or, in some cases, just two digits. Here’s how to decipher them:
Capacitors with Two Digits
When a capacitor is marked with only two numbers, the value is given directly in picofarads (pF). For example:
- 33 indicates a capacitance of 33 pF.
Capacitors with Three Digits
For capacitors with three digits, the interpretation involves a combination of tens, ones, and a multiplier:
- The first digit represents the tens.
- The second digit represents the ones.
- The third digit specifies the multiplier (in powers of 10).
Refer to the table below for common multipliers:
| Third Digit | Multiplier |
|---|---|
| 0 | ×1 |
| 1 | ×10 |
| 2 | ×100 |
| 3 | ×1,000 |
| 4 | ×10,000 |
| 5 | ×100,000 |
| 6-7 | Not Used |
| 8 | ×0.01 |
| 9 | ×0.1 |
Example of Three-Digit Codes
- A capacitor marked 102 means 10 followed by two zeros: 1,000 pF or 1 nF (0.001 µF).
- A capacitor marked 104 translates to 100 followed by four zeros: 100,000 pF or 100 nF (0.1 µF).
Below is a table illustrating additional examples:
| Code | Value (pF) | Value (nF) | Value (µF) |
|---|---|---|---|
| 10 | 10 | – | – |
| 100 | 100 | – | – |
| 101 | 100 | – | – |
| 102 | 1,000 | 1 | 0.001 |
| 103 | 10,000 | 10 | 0.01 |
| 104 | 100,000 | 100 | 0.1 |
| 105 | 1,000,000 | 1,000 | 1 |
Additional Letter Codes
Sometimes, a fourth character appears after the three-digit code, indicating the tolerance of the capacitor. For example, 102K denotes a capacitance of 1,000 pF with a tolerance of ±10%.
Here’s a guide to the tolerance letters:
| Letter | Tolerance |
|---|---|
| D | ±0.5 pF |
| F | ±1% |
| G | ±2% |
| H | ±3% |
| J | ±5% |
| K | ±10% |
| M | ±20% |
| P | +100%, -0% |
| Z | +80%, -20% |
Understanding these codes makes it easier to identify and use capacitors correctly in your projects.