The 3-digit EIA code uses two significant digits followed by a multiplier (number of zeros) in picofarads (pF). For example, 104 means 10 followed by 4 zeros = 100,000 pF, which converts directly to 100 nF or 0.1 µF. If you are replacing a component or designing a PCB, 104 (100nF) and 105 (1µF) are the most common decoupling values you will reach for.

Safety Warning: Before probing or replacing capacitors in mains-powered circuits (like ATX power supplies or tube amplifiers), de-energize the board and safely bleed large electrolytic capacitors using a high-wattage bleeder resistor. A 400V cap can hold a lethal charge for days.

How to Read This Capacitor Conversion Table

This reference table maps the physical markings on your component to its actual capacitance across three standard units: picofarads (pF), nanofarads (nF), and microfarads (µF). The marking standard is governed by IEC 60062 (international) and EIA-198 (North American) specifications.

Column Breakdown:

  • EIA 3-Digit Code: The physical marking on the capacitor body (e.g., 104). The first two digits are significant figures; the third digit is the multiplier (10^x).
  • pF / nF / µF: The nominal capacitance. Remember the shift: 1,000 pF = 1 nF; 1,000 nF = 1 µF.
  • Dielectric Class: The material inside the capacitor (C0G, X7R, Y5V). This dictates how stable the value is under heat and voltage.
  • DC Bias Derating Factor: The percentage of nominal capacitance you actually get when a DC voltage is applied (critical for Class II ceramics like X7R).

Bookmark tip: The rows for 103 (10nF), 104 (100nF), and 105 (1µF) account for 90% of everyday digital decoupling and filter designs. Jump straight to these when prototyping.

Master EIA Code to Farad Conversion & Derating Table

EIA Code pF (Picofarads) nF (Nanofarads) µF (Microfarads) Typical Dielectric DC Bias Derating Factor (at 50% Vr)
101 100 pF 0.1 nF 0.0001 µF C0G / NP0 100% (No loss)
102 1,000 pF 1 nF 0.001 µF C0G / X7R 95% - 100%
103 10,000 pF 10 nF 0.01 µF X7R / X5R 85% - 95%
104 100,000 pF 100 nF 0.1 µF X7R 70% - 85%
222 2,200 pF 2.2 nF 0.0022 µF C0G / X7R 95% - 100%
223 22,000 pF 22 nF 0.022 µF X7R 85% - 95%
224 220,000 pF 220 nF 0.22 µF X7R / X5R 60% - 80%
472 4,700 pF 4.7 nF 0.0047 µF C0G / X7R 95% - 100%
473 47,000 pF 47 nF 0.047 µF X7R 80% - 90%
474 470,000 pF 470 nF 0.47 µF X5R / X7R 50% - 70%
105 1,000,000 pF 1,000 nF 1.0 µF X5R / X7R 40% - 60%
225 2,200,000 pF 2,200 nF 2.2 µF X5R / Tantalum 30% - 50% (Ceramic)
475 4,700,000 pF 4,700 nF 4.7 µF X5R / Polymer 20% - 40% (Ceramic)
106 10,000,000 pF 10,000 nF 10.0 µF X5R / Tantalum 15% - 30% (Ceramic)

Source: Marking codes per IEC 60062; Dielectric classes and typical DC bias behaviors per EIA-198 and manufacturer datasheets (Murata, TDK).

Temperature and DC Bias Derating Rules

A common mistake on the bench is assuming a 10µF X5R ceramic capacitor will actually provide 10µF in your circuit. It won't. Which column applies to your installation depends entirely on the presence of DC voltage and the dielectric class.

The Golden Rule of Class II Ceramics: Barium titanate (the dielectric in X7R/X5R) loses permittivity when subjected to a DC electric field. If you apply 50% of the capacitor's rated voltage, a 10µF cap might drop to 4µF. If you apply 100% of the rated voltage, it can drop by 80% or more.

How derating rows modify the base value:
Look at the 105 (1µF) row. The base value is 1.0 µF. If your installation is a 5V power rail and you select a 6.3V rated X5R capacitor, you are operating at ~80% of the rated voltage (Vr). According to the derating factor column, your actual installed capacitance will be roughly 0.3 µF to 0.5 µF. To get a true 1µF at 5V, you must either buy a 16V or 25V rated capacitor (lowering the Vr percentage) or parallel two 1µF caps.

Which column applies to your installation?

  • Nominal Value Column (pF/nF/µF): Applies if you are using Class I dielectrics (C0G/NP0), film capacitors, or if the capacitor is used in a purely AC signal path with 0V DC bias (like audio AC-coupling).
  • Derated Value (Calculated via Factor Column): Applies if you are using Class II/III ceramics (X7R, X5R, Y5V) for DC power rail decoupling, bulk filtering, or snubber circuits where a constant DC voltage is present.

Decision Path: Selecting Dielectric and Value

Use this decision tree to terminate your component selection with a concrete pick. Do not default to 'it depends'—match your circuit environment to the row below.

Circuit Environment (Installation) IF your requirement is... THEN pick this Dielectric & Value
High-Frequency RF / Oscillator Tank Zero capacitance shift over temperature (-55°C to +125°C) and ultra-low ESR. C0G / NP0. Pick 101 (100pF) to 102 (1nF). Never use X7R here.
Digital IC Decoupling (MCU, FPGA, Logic) Fast transient response to supply high-frequency switching current spikes. X7R. Pick 104 (100nF) placed physically adjacent to the VCC pin, paired with a 105 (1µF) or 106 (10µF) bulk cap at the power entry.
Audio Signal Path / DAC Filtering Zero piezoelectric microphonics and low harmonic distortion. C0G Ceramic or Polypropylene Film. Pick 223 (22nF) or 473 (47nF). Avoid X7R entirely (it acts as a microphone).
Switching Regulator Output (Buck/Boost) High bulk capacitance to minimize output voltage ripple under heavy DC bias. Polymer Tantalum or Multi-layer X5R (Oversized). Pick 475 (4.7µF) to 106 (10µF) but rate the voltage at 2x your output rail.
Mains EMI / X2 Safety Filtering Must survive high-voltage AC transients without failing short. Metallized Polypropylene (Y2/X2 rated). Pick 104 (100nF) or 224 (220nF). Must bear UL/ENEC safety marks.

What This Table Cannot Tell You (Edge Cases)

A conversion chart gives you the nominal electrostatic value, but it hides the parasitic elements that will kill your circuit at high frequencies or high currents. When moving from the breadboard to a final PCB layout, you must consult the manufacturer's specific datasheet (e.g., from All About Circuits or vendor tools like Murata's SimSurfing) for the following missing parameters:

  1. ESR (Equivalent Series Resistance): Two different 105 (1µF) X7R capacitors from different manufacturers can have vastly different ESR. In a switching power supply, high ESR leads to excessive internal heating and catastrophic failure. Always check the ESR curve at your switching frequency.
  2. Ripple Current Rating: Primarily applies to electrolytic and tantalum capacitors. If your circuit pushes 2A of AC ripple current through a cap rated for 500mA, the internal dielectric will boil and vent, regardless of the capacitance value.
  3. Acoustic Noise (Piezoelectric Effect): Large physical size Class II ceramics (like 1206 or 1210 package X5R/X7R) physically vibrate when subjected to AC ripple in the audible range (20Hz - 20kHz). This causes 'singing capacitors' on motherboards and audio boards. The fix is using smaller package sizes, potting compound, or switching to film/C0G.
  4. Exact DC Bias Curves: The derating factors in our table are conservative bench-rule averages. The exact capacitance drop is non-linear. A 10µF 6.3V cap might hold 8µF at 1V, but plummet to 1.2µF at 5V. Always pull the specific vendor DC bias graph for power-rail bulk caps.

For a deeper dive into how these parasitics affect AC impedance, review the fundamental reactance formulas in standard references like Electronics Tutorials. Keep this chart on your bench for quick EIA code translation, but let the manufacturer datasheets dictate your final power-integrity sign-off.