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Capacitance Unit Converter

Convert capacitance between farads, millifarads, microfarads, nanofarads, and picofarads.

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Formula

1F=103mF=106muF=109nF=1012pF1 F = 10³ mF = 10⁶ mu F = 10⁹ nF = 10¹² pF

How It Works

This calculator converts between farads, microfarads, nanofarads, and picofarads for electronics engineers, PCB designers, and RF professionals. Per SI Brochure (BIPM), the farad is defined as C/V = A^2·s^4/(kg·m^2), representing the capacitance that stores 1 coulomb at 1 volt. Practical capacitors span 15 orders of magnitude: femtofarads for parasitic capacitance (0.1-1 fF per transistor gate), picofarads for RF matching (1-100 pF), nanofarads for filtering (1-1000 nF), microfarads for decoupling (0.1-100 uF), and farads for energy storage (1-3000 F supercapacitors). The EIA capacitor code system (104 = 100 nF) follows a 3-digit pattern: first two digits are significant figures, third digit is the power of 10 in picofarads.

Worked Example

Problem

A 100 nF decoupling capacitor for a 1.8 V, 500 mA switching load needs to limit voltage droop to 50 mV during a 100 ns current transient. Verify adequacy and select appropriate capacitor type.

Solution
  1. Capacitance: 100 nF = 0.1 uF = 100,000 pF = 10^-7 F
  2. Required charge: Q = I × t = 0.5 A × 100 × 10^-9 s = 50 nC
  3. Voltage droop: dV = Q / C = 50 × 10^-9 / 100 × 10^-9 = 0.5 V >> 50 mV target - INSUFFICIENT
  4. Required capacitance: C = Q / dV = 50 nC / 0.05 V = 1 uF minimum
  5. With 20% tolerance margin: use 1.5-2.2 uF ceramic (X5R or X7R per EIA-198)
  6. ESR check: at 10 MHz, X7R ESR ~10 mohm, impedance dominated by capacitance (16 mohm at 1 uF)

Practical Tips

  • ✓Capacitor code per EIA-198: 3 digits where first two are value, third is 10^n multiplier in pF. Examples: 104 = 10 × 10^4 pF = 100 nF = 0.1 uF; 222 = 22 × 10^2 pF = 2.2 nF; 101 = 10 × 10^1 pF = 100 pF
  • ✓Decoupling strategy per Intel/Xilinx guidelines: use 100 nF ceramic (handles MHz frequencies, ESL ~0.5 nH) in parallel with 10-100 uF tantalum/polymer (handles low-frequency bulk charge). Place 100 nF within 5 mm of IC power pins
  • ✓PCB parasitic capacitance per IPC-2141: 0.5-2 pF between adjacent traces at 100 mil spacing. This matters above 100 MHz where 1 pF at 1 GHz = 159 ohm reactance, potentially coupling signals between traces

Common Mistakes

  • ✗Confusing pF and nF - they differ by 1000x. A 100 pF capacitor has 1000x less capacitance than 100 nF. Writing '100' on a schematic without units is ambiguous: could be 100 pF or code 100 = 10 pF
  • ✗Ignoring DC bias derating for ceramic capacitors - Class II ceramics (X5R, X7R) lose 50-80% capacitance at rated voltage per EIA-198. A 10 uF/10V X5R at 8 VDC may have only 3 uF effective capacitance
  • ✗Entering wrong value in SPICE - '100n' works correctly, but '100' without suffix defaults to 100 F (not pF), giving nonsensical simulation results. Always include unit suffix: 100n, 100p, 100u

Frequently Asked Questions

Per EIA component surveys: RF capacitors are 0.5-100 pF for matching networks, ceramic decoupling 100 nF - 10 uF, aluminum electrolytics 10 uF - 10,000 uF. The nF/pF range spans high-frequency applications where capacitor ESL (typically 0.5-2 nH per EIA specs) becomes significant above 100 MHz.
Divide by 1000: 4700 pF = 4.7 nF = 0.0047 uF. Multiply by 1000 for reverse: 4.7 nF = 4700 pF. Standard E-series values per IEC 60063: E24 (5%) gives 4.7, 5.1, 5.6...; E12 (10%) gives 4.7, 5.6, 6.8... in any decade.
One farad stores 1 coulomb at 1 volt per SI definition: C = Q/V. In practical terms: 1 F at 5 V stores 5 joules of energy (E = 0.5 × C × V^2). A 3000 F supercapacitor at 2.7 V stores 10.9 kJ = 3 Wh, enough to power a 1 W device for 3 hours. Most electronics use uF or smaller.
Per EIA-198 marking standard: first two digits (10) are significant figures, third digit (4) is the 10^n multiplier in picofarads. So 104 = 10 × 10^4 pF = 100,000 pF = 100 nF = 0.1 uF. Common codes: 102 = 1 nF, 103 = 10 nF, 104 = 100 nF, 105 = 1 uF, 106 = 10 uF.

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