Article — Capacitance Conversion Calculator
Capacitance Conversion Across SI Prefixes
Capacitance conversion in the SI system moves a value between farads (F), millifarads (mF), microfarads (μF), nanofarads (nF), and picofarads (pF). Each step is exactly three powers of ten, so 1 μF = 1000 nF = 1,000,000 pF. The farad itself is defined as one coulomb of stored charge per volt of potential, and the smaller units exist because real components span fourteen orders of magnitude — from picofarads in radio circuits to kilofarads in modern supercapacitors.
Engineers move between these units constantly when reading schematics, comparing datasheets, or sizing decoupling networks. This calculator handles the conversion with exact factors and adjustable precision.
What is capacitance?
Capacitance is the ability of a component to store electric charge for a given voltage. The defining equation is C = Q / V, where C is capacitance in farads, Q is charge in coulombs, and V is voltage in volts. A 1 farad capacitor stores 1 coulomb of charge for every volt across its terminals.
Physically, a capacitor is two conductive plates separated by an insulator. When voltage is applied, opposite charges accumulate on each plate. The capacitance depends on plate area, plate spacing, and the permittivity of the insulator between them. Bigger plates, thinner gap, and higher-permittivity dielectric all increase capacitance.
The farad is named after Michael Faraday, the 19th-century English experimentalist who discovered electromagnetic induction. The unit was so large that for over a century no one made a 1 F component. The first commercial 1 F supercapacitor appeared in 1978; today you can buy 3000 F supercaps off the shelf.
Capacitance units in the SI system
The SI defines the farad as the base unit and uses standard SI prefixes for smaller and larger values. In capacitance practice you see milli (10⁻³), micro (10⁻⁶), nano (10⁻⁹), and pico (10⁻¹²). The kilo- and mega- prefixes are technically valid but rarely used because no traditional capacitor reaches 1000 F outside specialty energy-storage applications.
- farad (F) = base SI unit, 1 coulomb per volt
- millifarad (mF) = 10⁻³ F, used for some power-supply bulk caps
- microfarad (μF) = 10⁻⁶ F, audio, decoupling, motor-run caps
- nanofarad (nF) = 10⁻⁹ F, timing networks, filter caps
- picofarad (pF) = 10⁻¹² F, RF, oscillator load, trimmer caps
- vacuum permittivity ε₀ = 8.854 pF per meter
- supercapacitor range = 0.1 F to 5000 F per cell
Capacitance conversion rules
The conversion is straightforward because every prefix step is a factor of 1000. To go from a larger unit to a smaller, multiply by 1000 for each step. To go from a smaller to a larger, divide by 1000. The conversions are exact (defined by SI), so there is no rounding error other than what your calculator carries.
F × 1000 ↓mF × 1000 ↓μF × 1000 ↓nF × 1000 ↓pF ↑ ÷ 1000 each stepReading capacitor markings
Small ceramic capacitors use a three-digit code printed on the body. The first two digits are significant figures and the third is the multiplier (number of trailing zeros), with the final result in picofarads. So 104 means 10 followed by 4 zeros = 100,000 pF = 100 nF = 0.1 μF. The code 472 means 47 with 2 zeros = 4700 pF = 4.7 nF.
Larger electrolytic capacitors usually print the value directly — 100 μF, 1000 μF, 4700 μF — along with the voltage rating and a polarity stripe. Surface-mount caps too small for printed values rely on context: a 0402 ceramic between supply pins is almost certainly a 100 nF decoupler.
The letter following the value (K, M, J, etc.) is the tolerance code, not part of the value. 104K means 0.1 μF ±10%. 104J means 0.1 μF ±5%. Don't mistake the K for kilo (kF) — capacitance units this large basically don't exist outside supercapacitors.
Capacitance by application
Each capacitance range has typical homes. Power-supply bulk capacitors live in the tens to thousands of microfarads. Decoupling capacitors at IC supply pins are usually 100 nF. RF tuned circuits use pF caps for resonance, audio coupling caps run μF to tens of nF, and supercapacitors handle hold-up and burst-energy applications.
Capacitance tolerance and E-series
Real capacitors do not come in arbitrary values. They follow the E-series — a logarithmic distribution chosen so that adjacent values differ by enough to be meaningfully distinct given the tolerance. The E12 series has 12 values per decade (1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2), and most capacitors come in E12 or E24 spacings.
Tolerance grades are coded by letter: J = ±5%, K = ±10%, M = ±20%. Ceramic capacitors with X7R dielectric typically hit ±10% at room temperature but drift up to 15% across the operating range. Film and C0G ceramic caps are tighter (1-2%) but more expensive.
Common capacitance conversion mistakes
The most frequent error is misreading the prefix. The Greek letter μ (mu) for micro is sometimes typed as u (so uF = μF). The letter M is technically mega (10⁶) but is commonly misused for milli — always confirm context. A "100M" rating on an electrolytic almost certainly means 100 μF, not 100 MF.
The difference is a factor of one thousand. A 100 μF cap and a 100 mF cap differ by 1000×. Reading a schematic with the wrong scale can mean using a 100 mF (= 100,000 μF) electrolytic where a 100 μF was intended — vastly overspending and oversizing the part.
The second common slip is forgetting that ceramic-cap codes are in picofarads. A part marked 105 is 10 with 5 zeros = 1,000,000 pF = 1 μF, not 105 of anything. The two-significant-digit + exponent pattern is uniform across the industry.
Parasitic capacitance in real circuits
Every wire and trace has unavoidable capacitance to neighboring conductors. A typical PCB trace runs 1-2 pF per centimeter to ground, and a typical IC pin has 3-10 pF of input capacitance. These parasitic values matter in high-speed digital design and in RF circuits, where a stray 5 pF can shift a 100 MHz oscillator by 100 kHz or more.
Datasheets quote input capacitance in pF for op-amps, gate capacitance in pF for MOSFETs, and trace capacitance in pF/cm or fF/μm for IC layout. When converting between units in those domains, pico is almost always the right scale.