Capacitance Converter — farad, µF, nF, pF and CGS units

The capacitance converter above translates a value between farads and every prefix and legacy unit you are likely to encounter, including the electromagnetic abfarad and the electrostatic statfarad. Enter a number, choose the units, and the conversion appears live. The grid below the headline result always shows the same quantity in farads, microfarads, nanofarads and picofarads together, which is the fastest way to sanity-check a part number against a schematic.

Arb Digital publishes this alongside a wide set of free engineering converters because capacitance is the quantity where three different labelling conventions coexist for the same physical part. A 0.1 µF ceramic, a 100 nF ceramic and a 104-marked ceramic are identical components. Anyone reading datasheets from more than one region or more than one decade has to move between those forms constantly, and doing it in your head is where errors creep in.

What This Capacitance Converter Does

Capacitance measures how much electric charge a component stores for each volt applied across it. A capacitor with one farad of capacitance holds one coulomb of charge at one volt. That relationship — charge equals capacitance times voltage — is the whole definition, and it is why the farad is formally a coulomb per volt.

Like the henry, the farad is enormous compared with everyday components. Practical capacitors run from around a picofarad for a small ceramic trimmer up to several farads for a supercapacitor used in energy buffering, spanning roughly twelve orders of magnitude. Discrete capacitors above a few thousand microfarads are physically large electrolytics; anything quoted in whole farads is almost certainly a supercapacitor, not a conventional part.

This tool handles that entire span. It also includes the CGS units that appear in older literature, where a statfarad is sometimes written as a centimetre — an artefact of the electrostatic system in which capacitance carried a unit of length. If you have ever read an antique radio manual quoting a capacitor as "250 cm", that is 250 statfarads, which is about 278 picofarads.

How to Use It

1. Type your capacitance value. Use scientific notation for very small numbers if that is easier than counting zeros.
2. Select the source unit — whatever your datasheet, schematic or LCR meter reports.
3. Select the destination unit your calculation or parts list needs.
4. Read the result, which recalculates on every keystroke. The Convert button remains available for keyboard and assistive-technology users.
5. Press Swap units to reverse the conversion direction without re-entering anything.

The Formula: How Capacitance Conversion Is Calculated

All conversions run through the farad as a single pivot. The tool multiplies your value by the source unit's factor to reach farads, then divides by the destination unit's factor:

result = value × factor(from) ÷ factor(to)

For the SI prefixes those factors are exact powers of ten, defined in the BIPM SI Brochure: milli is 10⁻³, micro is 10⁻⁶, nano is 10⁻⁹ and pico is 10⁻¹². No rounding occurs anywhere in that chain, so converting from picofarads to microfarads and back returns the number you started with.

The CGS units are the only place approximation enters. The abfarad, the electromagnetic CGS unit, equals exactly 10⁹ F — a billion farads, which makes it a comically large unit and explains why it is almost never used. The statfarad equals approximately 1.112650056 × 10⁻¹² F, close to but not identical with the picofarad. That factor is the reciprocal of the same speed-of-light-squared constant that appears in the stathenry, which is why our inductance converter carries its mirror image. Conversion factors here follow NIST Special Publication 811.

Reference Table: Every Supported Unit

Each factor is the number of farads in one of that unit.

• farad (F) — 1 (SI base for this quantity)
• millifarad (mF) — 1 × 10⁻³ F
• microfarad (µF) — 1 × 10⁻⁶ F
• nanofarad (nF) — 1 × 10⁻⁹ F
• picofarad (pF) — 1 × 10⁻¹² F
• femtofarad (fF) — 1 × 10⁻¹⁵ F
• coulomb per volt (C/V) — 1 F exactly; the definition written out
• abfarad (abF) — 1 × 10⁹ F
• statfarad (statF) — 1.112650056 × 10⁻¹² F

Decoding Three-Digit Capacitor Markings

Small ceramic and film capacitors rarely have room to print a unit, so they use a three-digit code in which the first two digits are significant figures and the third is the number of zeros to append, with the result read in picofarads. A capacitor marked 104 is 10 followed by four zeros, or 100,000 pF. Convert that and you get 100 nF or 0.1 µF — the most common decoupling value in electronics, printed three different ways depending on who drew the schematic.

The trap is a two-digit marking. A part stamped simply "47" is 47 pF, not 47 of anything larger and not 47 followed by any zeros. Codes with an R, such as 4R7, use the R as a decimal point and mean 4.7 pF. Because these conventions overlap visually, the safe habit is to convert every value in a bill of materials into one working unit before comparing anything. Running the whole list through picofarads makes an outlier obvious at a glance.

Why Nanofarads Are Common in Europe and Rare in the US

American schematics historically jump straight from microfarads to picofarads, writing 0.001 µF where a European drawing would write 1 nF. Both are correct and both describe the identical part. The convention gap survives because it predates widespread SI adoption in electronics and because component distributors index their catalogues in whichever unit their market expects.

This matters for anyone sourcing parts across regions. Searching a distributor for "1 nF" and searching for "0.001 µF" can return different result sets even though the parts are interchangeable, simply because the search matches a text field rather than a converted value. Converting your target value into all three common units before searching — which the grid on this page does automatically — reliably widens the net.

Capacitance Is Not Fixed: Tolerance, Voltage and Temperature

A converted number is exact, but the component it describes is not. Ceramic capacitors using class 2 dielectrics such as X7R and Y5V lose capacitance as DC bias voltage rises, sometimes dramatically — a part rated 10 µF can measure a fraction of that when operated near its rated voltage. Temperature adds another swing, and the dielectric code tells you how much: an X7R part is specified over a defined temperature band with a stated percentage tolerance, while Y5V permits a far wider drift.

The practical consequence is that converting 10 µF to 10,000 nF does not mean your circuit sees 10,000 nF. It means the nameplate value is 10,000 nF under the manufacturer's measurement conditions. For filtering and timing circuits where the actual value matters, designers routinely derate, or choose C0G/NP0 dielectrics whose capacitance is far more stable. Unit conversion and component tolerance are separate problems, and only the first one has an exact answer.

Using Capacitance in Time Constants and Resonance

The two calculations that consume capacitance values most often are the RC time constant and the LC resonant frequency. The time constant is simply resistance times capacitance, and it produces a result in seconds only when resistance is in ohms and capacitance is in farads. A 10 kΩ resistor with a 100 nF capacitor gives 10,000 × 1 × 10⁻⁷ = 0.001 seconds, or one millisecond. Feeding kilohms and nanofarads into that multiplication without converting yields a number that is wrong by six orders of magnitude.

The same discipline applies to resonance, where the frequency depends on the square root of the product of inductance and capacitance, again in coherent base units. For the resistance side of a time constant use our resistance converter, for the inductance side the inductance converter, and to move the resulting frequency between hertz and megahertz the frequency converter. Charge stored on a capacitor at a given voltage is handled by the electric charge converter, since charge equals capacitance times voltage.

Series and Parallel: Capacitance Adds Backwards

Resistors in series add directly and resistors in parallel combine reciprocally. Capacitors do the opposite, and this trips people up more often than the unit conversions do. Capacitors in parallel add their capacitances straight up: two 100 nF parts in parallel give 200 nF. Capacitors in series combine reciprocally, so two 100 nF parts in series give 50 nF — less than either one alone.

The physical reason is that series capacitors share the applied voltage while carrying the same charge, so the effective charge stored per volt drops. This is why bulk decoupling banks are wired in parallel, and why series stacking is used to raise voltage rating rather than capacitance. It also means that when you convert a target capacitance into a component selection, you should decide the topology before converting: a design calling for 220 µF might be met by two 470 µF parts in series with double the voltage headroom, and the arithmetic only works if both values are expressed in the same unit first.

Equivalent series resistance, usually written ESR, is the other property that decides whether a nominally correct capacitance actually performs. A 1,000 µF electrolytic and a 1,000 µF polymer capacitor convert identically to 1 mF, but their ESR can differ by more than an order of magnitude, and in a switching supply that difference determines ripple voltage and self-heating. ESR is quoted in milliohms, which is where the resistance converter earns its place beside this one.

Energy Stored in a Capacitor

A charged capacitor stores energy equal to one half of the capacitance multiplied by the square of the voltage. Because that formula is quadratic in voltage, doubling the working voltage quadruples the stored energy while doubling the capacitance only doubles it — the reason high-energy capacitor banks push voltage rather than capacitance where the dielectric allows.

Running the numbers requires farads and volts, not microfarads and volts, which is the practical reason this converter exists. A 4,700 µF capacitor at 400 volts stores 0.5 × 0.0047 × 160,000 = 376 joules. That is a genuinely dangerous amount of energy stored in a component small enough to hold, which is why large electrolytics in power equipment carry bleed resistors and why service procedures require a discharge step before anyone touches the board. Convert the capacitance to farads, square the voltage, and the joule figure tells you immediately whether a bank deserves respect.

Common Mistakes to Avoid

• Reading a three-digit code as a literal value — 104 means 100,000 pF, not 104 pF.
• Assuming a statfarad equals a picofarad — it is about 11 percent larger, at 1.1127 pF.
• Mixing kilohms with nanofarads in an RC time constant instead of converting to ohms and farads first.
• Treating the printed value as the operating value — DC bias and temperature can move class 2 ceramics a long way from nameplate.
• Searching a distributor in only one unit — 0.001 µF and 1 nF are the same part but often index differently.

Related Free Tools From Arb Digital

Use the inductance converter for the henry side of a resonant circuit, the resistance converter for ohms, and the electric charge converter for coulombs and amp-hours. The energy converter helps when working out the joules stored in a capacitor, and the frequency converter covers the output of any resonance calculation. Everything else lives in the free online tools hub.

Frequently Asked Questions