Capacitance Unit Converter

How to use this calculator

Capacitance value — enter your number. The screenshot shows 100 µF converting to nanofarads: 100,000 nF. That’s the unit-hop that trips people up most often in filter design.

From unit — the unit your value is already in. The dropdown includes farads (F), millifarads (mF), microfarads (µF), nanofarads (nF), and picofarads (pF).

To unit — the unit you want as the primary output.

The output panel shows all four reference values simultaneously: F, mF, nF, pF. The capacitor size reference chart below it maps your value against physical component types, from 100 pF ceramic discs to 1 F supercapacitors. That chart is the part that anchors the numbers to something you can actually hold.

Why the farad is a useless unit in practice

The farad is the SI unit of capacitance. You will almost never see a component rated in farads.

A 1-farad capacitor is enormous by the standards of most electronics. The first commercially practical 1 F capacitors were supercapacitors that physically resembled small batteries, not the disc or cylinder components in typical circuits. A standard electrolytic capacitor in a PC power supply is 1,000 µF — that’s 0.001 F. A ceramic bypass capacitor on a logic chip is 100 nF — 0.0000001 F. Expressing either in farads produces numbers so small they obscure the component’s behavior.

So everyone uses sub-farad units. Mostly µF and nF, sometimes pF for RF and high-frequency work.

The farad does appear in supercapacitor specs (Maxwell sells a 3,000 F cell), in physics calculations where you want clean SI units, and on the converter’s output panel as the reference anchor. Everywhere else: µF, nF, or pF.

The conversion structure

Capacitance is all powers of 1,000. There’s no cross-family factor like the 3,600 in charge conversion or the 4,184 in energy conversion. Just metric prefixes.

So:

• 1 F = 1,000 mF = 1,000,000 µF = 1,000,000,000 nF = 1,000,000,000,000 pF
• 1 µF = 1,000 nF = 1,000,000 pF
• 1 nF = 1,000 pF

The math is simple. The errors happen when someone reads a value off a schematic in nF, finds a component spec in µF, and multiplies instead of divides — or just forgets which direction they’re going.

Common conversions at a glance

The µF-to-nF and nF-to-pF conversions are the ones circuit designers need most. Both are just × 1,000 or ÷ 1,000 depending on direction.

Capacitor types by size range

The capacitor size reference chart in the calculator maps your value against five physical component families. Here’s what each range actually means in practice.

pF range (picofarads): 1 pF – ~1,000 pF

Ceramic disc capacitors dominate this range. Small, cheap, physically tiny, stable across temperature and voltage. Used for bypassing high-frequency noise on signal lines, RF tuning circuits, timing in crystal oscillators, and parasitic capacitance compensation.

A 100 pF ceramic is about 4mm across. You can fit 50 of them in a thimble.

Common pF values you’ll see on schematics: 10 pF, 22 pF, 33 pF, 47 pF, 100 pF. These precise values come from the E12 and E24 series standardized component values.

nF range (nanofarads): 1 nF – ~1,000 nF

Film capacitors (polyester, polypropylene) own this range, alongside ceramic multilayer. Better AC characteristics than electrolytics. Lower ESR than most electrolytics. Used in audio crossovers, snubber circuits across relay contacts, motor run capacitors, and general-purpose filtering.

A 100 nF (0.1 µF) ceramic capacitor in an MLCC package is the single most common bypass capacitor in digital electronics. If a datasheet says “place 100 nF ceramic close to each VCC pin,” it means this range.

µF range (microfarads): 1 µF – ~10,000 µF

Two types compete here: electrolytic (aluminum or tantalum) and large-value MLCC ceramics.

Electrolytics are polarized — they have a positive and negative leg, and reversing the voltage destroys them. They’re cheap, high-capacitance-per-volume, and have higher ESR than film or ceramic. Power supply bulk filtering is their primary job.

Large-value MLCCs (1 µF–100 µF) have entered this range over the last decade as ceramic manufacturing improved. They’re non-polarized and have lower ESR, making them better for some decoupling applications, but they’re physically larger and more expensive than electrolytics at equivalent capacitance.

The 100 µF value in the calculator screenshot sits squarely in the electrolytic zone.

mF range (millifarads): 10 mF – ~1,000 mF

Supercapacitors (also called ultracapacitors or electric double-layer capacitors) start appearing here. Some high-value electrolytics reach 10–100 mF, but above ~0.1 F you’re generally in supercap territory.

These have extraordinarily low ESR and can deliver or absorb current spikes that would destroy a battery in the same time. Common uses: UPS backup for microcontrollers (keep SRAM alive during power loss), regenerative braking energy capture in small devices, camera flash circuits, automotive start-stop systems.

They don’t work well at high voltages. Most supercap cells are rated 2.5–2.7 V. Stack them in series to get higher voltage ratings.

F range (farads): 1 F and above

Large supercapacitor modules. A 1 F supercap can supply 1 A for 1 second, or 100 mA for 10 seconds. Used in industrial UPS systems, hybrid vehicle energy buffers, grid-scale momentary power smoothing.

Maxwell (now Eaton) makes supercapacitor banks at 3,000 F. These are not components you put on a PCB. They’re the size of a small toolbox.

Real-world examples

Reading a capacitor code

Ceramic disc capacitors often use a three-digit code instead of printing the value directly. “104” means 10 × 10⁴ pF = 100,000 pF = 100 nF = 0.1 µF.

The first two digits are the base value. The third is the multiplier (number of zeros). So “472” = 47 × 10² pF = 4,700 pF = 4.7 nF.

Electrolytic capacitors just print the value in µF directly on the side, along with the voltage rating. A capacitor marked “1000µF 16V” is 1,000 µF, rated to 16 volts. That’s 1 mF or 1,000,000 nF. The converter gives you all four simultaneously.

RC circuit time constant

A resistor-capacitor circuit’s time constant τ (tau) is how long it takes the capacitor to charge to about 63% of the supply voltage.

τ = R × C

Where R is in ohms and C is in farads.

An RC circuit with a 10 kΩ resistor and 100 µF capacitor:

τ = 10,000 × 0.0001 = 1 second

Same circuit, but the capacitor value is listed as 100,000 nF on the component spec:

100,000 nF = 100 µF. The time constant is the same, but you have to convert first or you’ll plug in 100,000 instead of 0.0001 and get a result that makes no sense.

This is the most common place capacitance unit confusion causes real errors in circuit calculations.

Filter cutoff frequency

A low-pass RC filter’s cutoff frequency:

f = 1 / (2π × R × C)

For a 10 kΩ resistor and 10 nF capacitor:

f = 1 / (2π × 10,000 × 0.00000001) = 1,592 Hz

If you mistakenly plug in 10 instead of 0.00000001 (forgetting to convert nF to F):

f = 1 / (2π × 10,000 × 10) = 0.0016 Hz

That’s a cutoff frequency of once every 10 minutes. Off by nine orders of magnitude. The calculation is technically consistent with the unit error, which is exactly what makes these mistakes hard to catch without double-checking units.

Supercapacitor runtime calculation

A 10 F supercapacitor at 2.5 V powers a microcontroller drawing 50 mA during a power outage. How long does it last?

Energy stored: E = ½ × C × V² = 0.5 × 10 × 2.5² = 31.25 J

Power drawn: P = V × I = 2.5 × 0.05 = 0.125 W

Runtime: t = E / P = 31.25 / 0.125 = 250 seconds ≈ 4 minutes

In practice it’ll be less, because the supercap voltage drops as it discharges and the microcontroller will brown out before the cap reaches 0 V. Add a boost converter to regulate voltage and you recover most of that runtime.

This calculation requires capacitance in farads (10 F, already in the right unit) and shows why the farad is useful in physics — even if the component was labeled in millifarads on the spec sheet.

Parasitic capacitance in PCB traces

A PCB trace over a ground plane has parasitic capacitance on the order of 1–3 pF per centimeter. A 10 cm trace has about 10–30 pF.

At low frequencies: irrelevant.

At 1 GHz: a 30 pF parasitic capacitance has an impedance of 1 / (2π × 10⁹ × 0.000000000030) = 5.3 Ω. Now it’s affecting signal integrity.

This is why RF engineers think in picofarads and why high-speed digital design involves careful trace length management. The converter isn’t doing the impedance calculation, but getting the pF-to-F conversion right is the first step before plugging into any RF formula.

The µF marking problem on old capacitors

Older capacitors — and some cheap modern ones — use abbreviations that aren’t quite standard.

“MFD” on old electrolytics means microfarads (µF). “MMFD” or “µµF” means picofarads (pF, historically called “micro-microfarads”). If you’re restoring vintage audio equipment or a tube amplifier and the schematic says “0.01 MFD,” that’s 0.01 µF = 10 nF = 10,000 pF.

Some European schematics from the 1960s–80s use “n” for nanofarads directly: “10n” means 10 nF. Others use “p” for picofarads. Consistent, at least.

The converter handles current standard notation. For vintage work, confirming the original abbreviation convention is the first step before converting anything.

Where capacitance unit errors cost you

Wrong value in an RC timer. A 555 timer circuit tuned to 1 kHz with a 10 nF capacitor will oscillate at 1 Hz if you accidentally install a 10 µF capacitor instead. Both are small, similar-looking ceramic or film components. The difference is 1,000×, which shows up immediately once the circuit is powered.

Polarity on electrolytics. The µF value is only part of reading an electrolytic. The voltage rating matters equally. A 100 µF 10 V capacitor will fail — sometimes violently — if the circuit runs at 12 V. The converter handles the capacitance unit. Voltage derating is a separate lookup.

Assuming “nF” on a schematic means “mF.” Occasionally happens when reading quickly. n and m look similar in certain fonts and handwriting. 100 nF and 100 mF differ by a factor of 1,000,000. In a power supply design, that error produces a component physically the size of a soup can where a small MLCC should go.

Ceramic capacitor DC bias derating. High-K MLCC capacitors (X5R, X7R) lose significant capacitance under DC bias voltage. A 10 µF X5R ceramic at its rated voltage might only deliver 4–6 µF in circuit. This isn’t a unit conversion issue, but it means the “10 µF” on the component label isn’t always what the circuit sees. Worth knowing when the converter gives you a clean number and the circuit still misbehaves.

Full unit reference table

The bottom line

Capacitance conversion is the simplest of the electrical unit conversions: every step is × 1,000 or ÷ 1,000. The only arithmetic you need is knowing which direction.

The practical range for most circuit work sits between 1 pF and 10,000 µF. Below 1 pF you’re dealing with parasitic effects. Above 10,000 µF you’re in supercapacitor territory.

The converter outputs all four representations simultaneously — F, mF, nF, pF — so you can see the same value in the unit your datasheet uses and the unit your formula needs without running it twice. The capacitor size reference anchors the number to a physical component type so “100,000 nF” stops being abstract and becomes “that’s a 100 µF electrolytic, same size as the one on the power supply board.”

Units are labels. The capacitor doesn’t care which one you use. The formula does.