If you are staring at a tiny ceramic capacitor stamped with 104, the direct answer is that it equals 100,000 picofarads (pF), which converts to 100 nanofarads (nF) or 0.1 microfarads (µF). This 3-digit marking system, governed by IEC 60062 and EIA standards, is the universal shorthand for through-hole and surface-mount capacitors where physical space prevents printing the full value.
But reading the base capacitance is only half the battle. To actually use the component in a power supply filter or an RF matching network, you need to understand the tolerance letters, voltage prefixes, and—most critically—how dielectric materials derate that base value under real-world DC bias.
How to Read the Capacitor Codes Chart (EIA & IEC Standards)
The standard capacitor code consists of three digits followed by an optional letter. The first two digits are the significant figures, and the third digit is the multiplier (the number of zeros to add). The base unit is always picofarads (pF).
If you are designing high-frequency RF filters or oscillator tank circuits, use the Base pF column, as RF calculations rely on exact picofarad values. If you are doing general power decoupling, audio coupling, or breadboarding, use the Converted nF/µF column, which aligns with how power supply ripple and timing constants are typically calculated.
The optional letter following the numbers indicates tolerance (e.g., J = ±5%, K = ±10%, M = ±20%). Sometimes, a prefix letter and number (like 1H or 1E) indicate the voltage rating based on JIS/EIA standard voltage codes.
The Master Capacitor Codes Chart (Capacitance, Tolerance, and Voltage)
The table below covers the most queried values you will encounter when sorting through a bulk bin of Murata, KEMET, or TDK capacitors. Bookmark this section for quick bench reference.
| 3-Digit Code | Multiplier | Base Value (pF) | Converted (nF / µF) | Common Application |
|---|---|---|---|---|
| 101 | × 10 | 100 pF | 0.1 nF | RF bypass, VCO tuning |
| 102 | × 100 | 1,000 pF | 1 nF | Snubber circuits, EMI filtering |
| 103 | × 1,000 | 10,000 pF | 10 nF | High-freq decoupling, audio tone |
| 104 | × 10,000 | 100,000 pF | 100 nF (0.1 µF) | Standard IC VCC decoupling |
| 105 | × 100,000 | 1,000,000 pF | 1,000 nF (1 µF) | Bulk local decoupling, timing |
| 106 | × 1,000,000 | 10,000,000 pF | 10 µF | Power supply bulk filtering |
| 224 | × 10,000 | 220,000 pF | 220 nF (0.22 µF) | Audio coupling, active filters |
| 473 | × 1,000 | 47,000 pF | 47 nF | Switch-mode power supply snubbers |
| 474 | × 10,000 | 470,000 pF | 470 nF (0.47 µF) | Motor start/run, AC line filtering |
Source Standard: Marking codes per IEC 60062 (International Electrotechnical Commission) and EIA RS-198 for dielectric classifications.
Tolerance and Voltage Modifier Codes
The base 3-digit code is often followed or preceded by modifiers. Here are the most common bench-level modifiers:
- Tolerance Letters: C (±0.25pF), D (±0.5pF), J (±5%), K (±10%), M (±20%), Z (+80% / -20%).
- Voltage Prefixes (JIS/EIA): 0J (6.3V), 1A (10V), 1C (16V), 1E (25V), 1H (50V), 2A (100V).
Example: A capacitor marked 1H 104 K is a 50V, 100nF (0.1µF) capacitor with a ±10% tolerance.
Dielectric Codes and DC Bias Derating (What the Base Code Hides)
A common trap for DIY builders and junior engineers is assuming a 106 (10µF) capacitor will actually provide 10µF in circuit. The 3-digit code only tells you the nominal capacitance measured at 1 kHz with a low AC signal and zero DC bias. In reality, the dielectric material heavily derates this value when DC voltage is applied.
The table below shows how the Dielectric Derating Modifier (governed by EIA RS-198) modifies the base code value under typical rated DC bias.
| Dielectric Code | Temperature Range | Capacitance Change | DC Bias Derating Factor | Real-World Example (Base 106 / 10µF) |
|---|---|---|---|---|
| C0G / NP0 | -55 to +125°C | ±30 ppm/°C | 1.0x (No derating) | Remains 10µF (Rare in high values) |
| X7R | -55 to +125°C | ±15% | 0.4x to 0.8x | Drops to ~4µF - 8µF at rated voltage |
| X5R | -55 to +85°C | ±15% | 0.3x to 0.7x | Drops to ~3µF - 7µF at rated voltage |
| Y5V | -30 to +85°C | +22% / -82% | 0.1x to 0.3x | Drops to ~1µF - 3µF (Avoid for power) |
Standard code charts do not provide Equivalent Series Resistance (ESR), Equivalent Series Inductance (ESL), or the physical footprint (e.g., 0402 vs. 0805). Furthermore, the exact DC bias curve is non-linear and specific to the manufacturer's physical stack design. A Murata GRM21BR71H105K (0805 1µF 50V X7R) will derate differently than a KEMET C0805C105K5RACTU, even though both share the same base codes. Always verify critical power-rail capacitance using manufacturer tools like Murata's SimSurfing or KEMET's KSIM.
Frequently Asked Questions (FAQ)
What does the letter 'J' or 'K' mean on a capacitor code?
The letters indicate the manufacturing tolerance of the capacitance value. J means the actual capacitance is within ±5% of the nominal code value, while K means ±10%. For example, a 104K capacitor (nominally 100nF) is guaranteed by the manufacturer to measure between 90nF and 110nF at room temperature with no DC bias applied. In power decoupling, K and M (±20%) are perfectly acceptable, but in precision timing circuits (like a 555 timer astable oscillator) or RF filters, you should source J or tighter tolerance parts.
How do I convert a 3-digit capacitor code to microfarads (µF)?
Take the first two digits, multiply by 10 to the power of the third digit, and you have picofarads (pF). To convert to microfarads (µF), divide that result by 1,000,000.
Shortcut method: If the third digit is 4, move the decimal four places to the left to get µF.
Example: Code 224 -> 22 + 0000 = 220,000 pF. Divide by 1,000,000 = 0.22 µF.
If the third digit is 5, move the decimal five places. Code 475 -> 47 + 00000 = 4,700,000 pF = 4.7 µF.
Why does my 106 (10µF) X7R capacitor measure much lower on my multimeter?
There are two primary reasons for this. First, cheap handheld multimeters often struggle to accurately measure high-value ceramic capacitors due to the meter's own test frequency and internal resistance. Second, and more importantly, if you are measuring the capacitor while it is in-circuit, parallel impedance paths will skew the reading. However, if you are measuring a bare 106 X7R or Y5V capacitor and it reads 4µF, you are likely witnessing the DC bias derating mentioned in our chart above, or the capacitor has suffered from dielectric absorption and aging. Class II dielectrics (X7R, X5R) lose capacitance as they age and as DC voltage is applied. If you need a true, stable 10µF that measures 10µF under load, you must switch to a tantalum, aluminum electrolytic, or a much larger physical footprint ceramic capacitor rated for a significantly higher voltage than your operating rail.
