A capacitance value chart translates the standard 3-digit EIA codes printed on physical components into usable picofarad (pF), nanofarad (nF), and microfarad (µF) values, while simultaneously defining the voltage and temperature derating limits required for reliable circuit operation. The first two digits are significant figures, and the third digit is the multiplier (number of zeros) in picofarads. For example, a code of 104 means 10 followed by 4 zeros = 100,000 pF, which equals 100 nF or 0.1 µF.
However, reading the code is only step one. If you apply 16V to a 16V-rated 10µF X7R ceramic capacitor, you will not get 10µF; you might get 3µF due to DC bias derating. This reference guide provides the complete conversion table alongside the critical derating multipliers dictated by Cornell Dubilier's application guidelines and IEC 60384-1 standards.
How to Read the Capacitance Value and Derating Table
The table below merges the EIA RS-279 capacitance code standard with practical derating rules derived from Vishay's ceramic capacitor DC bias notes and MIL-PRF-55364 specifications. Here is how to apply the columns to your specific installation:
- Which column applies to your installation? Use the pF column for RF tuning, oscillator tanks, and high-speed digital edge-rate control. Use the nF column for audio coupling, EMI filtering, and intermediate decoupling. Use the µF column for bulk power supply filtering, low-frequency timing circuits, and motor start/run applications.
- How to use the Derating Multiplier: This column tells you the maximum percentage of the rated voltage you should actually apply. For solid tantalum capacitors, the multiplier is typically 0.5 (50%). If your circuit runs at 12V, you must select a capacitor rated for at least 24V (12V / 0.5). For Class II ceramics (X7R/X5R), DC bias derating reduces the actual capacitance under voltage, meaning a 10µF part at its rated voltage might only provide 30% of its nominal value.
The Master Capacitance Value & Derating Chart
Bookmark this section for quick bench lookups. The most frequently queried values on the workbench (103, 104, 105, 224, 474) are marked with quick-jump IDs.
| EIA Code | Picofarads (pF) | Nanofarads (nF) | Microfarads (µF) | Typical Dielectric | Voltage Derating Rule |
|---|---|---|---|---|---|
| 102 | 1,000 | 1 | 0.001 | C0G / NP0 | Apply up to 100% rated V |
| 103 | 10,000 | 10 | 0.01 | X7R / Film | Derate 20% for X7R at Vmax |
| 104 | 100,000 | 100 | 0.1 | X7R / Y5V | Derate 40% for Y5V, 20% X7R |
| 223 | 22,000 | 22 | 0.022 | X7R / C0G | Apply up to 100% for C0G |
| 224 | 220,000 | 220 | 0.22 | X7R / Film | Derate 20% for X7R at Vmax |
| 473 | 47,000 | 47 | 0.047 | X7R / Film | Derate 20% for X7R at Vmax |
| 474 | 470,000 | 470 | 0.47 | X5R / X7R | Derate 30-50% depending on Vdc |
| 105 | 1,000,000 | 1,000 | 1.0 | X5R / Tantalum | Derate 50% for Solid Tantalum |
| 225 | 2,200,000 | 2,200 | 2.2 | X5R / Tantalum | Derate 50% for Solid Tantalum |
| 475 | 4,700,000 | 4,700 | 4.7 | X5R / Tantalum | Derate 50% for Solid Tantalum |
| 106 | 10,000,000 | 10,000 | 10.0 | X5R / Aluminum | Derate 20% for Al Electrolytic |
What the Chart Cannot Tell You: Hidden Failure Modes
A standard capacitance value chart is a static lookup tool. It cannot tell you the dynamic behavior of the component under real-world stress. When designing power supplies or precision analog circuits, you must look beyond the nominal µF value and consult the component datasheet for the following parameters:
- Equivalent Series Resistance (ESR): Two 100µF aluminum electrolytic capacitors might share the same code, but a low-ESR variant (like the Panasonic FR series) can handle 10x the ripple current of a standard variant without overheating and venting.
- Dielectric Absorption (DA): Also known as 'soakage', this is the tendency of a capacitor to retain a residual charge after being discharged. Teflon and C0G ceramics have near-zero DA, making them mandatory for sample-and-hold circuits, whereas high-K ceramics and electrolytics can introduce significant measurement errors.
- Microphonic Noise (Piezoelectric Effect): Class II ceramics (X7R, X5R) are piezoelectric. Mechanical vibration from a cooling fan or a nearby transformer will cause the dielectric to generate parasitic voltage spikes. If you are building a high-gain audio preamp or a sensitive RF receiver, you must use non-piezoelectric C0G/NP0 ceramics or film capacitors in the signal path, regardless of what the capacitance code suggests.
- Temperature Coefficient (Tempco): A Y5V capacitor can lose up to 80% of its capacitance just by heating from 20°C to 85°C. Never use Y5V for timing circuits or power rail decoupling; stick to X7R or X5R for general purpose, and C0G for precision.
Frequently Asked Questions
What does the letter suffix (J, K, M) mean on a capacitance code?
The letter immediately following the 3-digit capacitance code indicates the manufacturing tolerance. J means ±5%, K means ±10%, and M means ±20%. For example, a capacitor marked '104K' is a 100nF (0.1µF) capacitor with a tolerance of ±10%, meaning its actual measured value will fall between 90nF and 110nF. For precision timing circuits using 555 timers or RC oscillators, always specify J (5%) or F (1%) tolerance parts.
Why does my 10µF X7R capacitor measure 3µF in-circuit?
This is the DC bias effect, a fundamental characteristic of Class II (barium titanate) ceramic dielectrics. As the DC voltage across the capacitor increases, the dielectric's permittivity drops dramatically. A 10µF, 16V X7R capacitor in an 0805 package might only provide 3µF of actual capacitance when 12V is applied. To fix this, either choose a larger physical package (like 1210), select a higher voltage rating (like 50V) to keep the operating voltage in the linear region of the curve, or parallel multiple smaller values.
Can I substitute a 105°C electrolytic for an 85°C part?
Yes, substituting a 105°C capacitor (like the Nichicon UHE series) for an 85°C part is generally an excellent upgrade that will significantly extend the lifespan of the equipment, especially in enclosed power supplies. The rule of thumb is that for every 10°C drop in operating temperature, the electrolytic capacitor's lifespan doubles. However, be aware that some 105°C low-ESR capacitors have a slightly higher ESR at room temperature compared to 85°C general-purpose parts, which is rarely an issue unless you are working on highly specific legacy audio crossover networks.
How do I find the physical package size from a capacitance value chart?
You cannot determine physical size strictly from a capacitance value chart. The physical volume of a capacitor is dictated by its 'CV product' (Capacitance × Voltage) and the specific dielectric material used. A 10µF 6.3V ceramic capacitor might fit in a tiny 0402 surface mount package, while a 10µF 450V aluminum electrolytic capacitor will be the size of a soda can. Always check the manufacturer's mechanical dimensions table after selecting your electrical values.
