Capacitance Converter (pF, nF, µF)
Capacitance Converter (pF, nF, µF)
Convert a capacitance between picofarads, nanofarads, microfarads, millifarads and farads — or start from the three-digit code printed on the part — and see the value in every unit at once, with the three-digit marking and the reactance at a frequency you choose.
Capacitance units
A ceramic capacitor marked 104
Capacitance units and the printed code
- pF
- picofarad, 10⁻¹² F — ceramics, crystal loads, RF
- nF
- nanofarad, 10⁻⁹ F — the decoupling and filtering range
- µF
- microfarad, 10⁻⁶ F — electrolytics, tantalums, bulk storage
- 104
- 10 followed by four zeros, in picofarads: 100,000 pF = 100 nF
- mF, F
- millifarad and farad — rare on markings; a 4,700 µF reservoir is 4.7 mF, and a supercapacitor really is farads
Worked example
A ceramic capacitor marked 104
The first two digits are the figures: 10
The third is the number of zeros to add, in picofarads: 4
10 followed by four zeros = 100,000 pF
100,000 pF = 100 nF = 0.1 µF — the same part, three ways of writing it
At 1 kHz its reactance is 1.592 kΩ
The units
| Unit | In farads | In pF | Where you see it |
|---|---|---|---|
| picofarad (pF) | 10⁻¹² F | 1 | Ceramic capacitors, crystal loads, RF tuning |
| nanofarad (nF) | 10⁻⁹ F | 1,000 | Decoupling, filters, timing |
| microfarad (µF) | 10⁻⁶ F | 1,000,000 | Electrolytics, tantalums, motor-run capacitors |
| millifarad (mF) | 10⁻³ F | 1,000,000,000 | Rarely printed; 4,700 µF is 4.7 mF |
| farad (F) | 1 F | 10¹² | Supercapacitors, and the SI unit itself |
Values a beginner meets, in every unit
| Value | pF | nF | µF | Code | What it is usually for |
|---|---|---|---|---|---|
| 22 pF | 22 | 0.022 | 0.000022 | 220 | Crystal load capacitors, one each side of a quartz crystal |
| 100 pF | 100 | 0.1 | 0.0001 | 101 | RF coupling and small timing capacitors |
| 1 nF | 1,000 | 1 | 0.001 | 102 | Snubbers, filter capacitors, the small end of audio coupling |
| 10 nF | 10,000 | 10 | 0.01 | 103 | General filtering and coupling |
| 100 nF | 100,000 | 100 | 0.1 | 104 | Decoupling: one beside every logic chip’s supply pin |
| 1 µF | 1,000,000 | 1,000 | 1 | 105 | Coupling and local supply smoothing |
| 10 µF | 10,000,000 | 10,000 | 10 | 106 | Bulk decoupling on a board, regulator output capacitor |
| 470 µF | 470,000,000 | 470,000 | 470 | 477 | Reservoir capacitor after a rectifier |
| 4,700 µF | 4,700,000,000 | 4,700,000 | 4,700 | 478 | Mains power-supply reservoir, large audio amplifier rails |
Picofarads, nanofarads and microfarads
The farad is an enormous unit. One farad holds a coulomb of charge at one volt, and until supercapacitors arrived nothing on a circuit board came close, so every capacitor you will meet is labelled in some fraction of it. The three that matter are the picofarad (10⁻¹² F), the nanofarad (10⁻⁹ F) and the microfarad (10⁻⁶ F), and they are exactly a thousand apart: 1 µF = 1,000 nF = 1,000,000 pF. Nothing more complicated than moving a decimal point three places at a time.
Why the same part gets written three ways. The commonest capacitor in electronics, the one beside every logic chip’s supply pin, is 100 nF. European schematics call it 100n, American ones 0.1 µF, its own body says 104, and a datasheet might write 100,000 pF. All four are the same part. This page shows every form at once so you can match a parts list against a schematic against the thing in your hand.
The printed code. Small ceramic and film capacitors are marked with three digits: two figures and then the number of zeros to add, the result being in picofarads. 104 is 10 with four zeros, 100,000 pF, which is 100 nF. 221 is 220 pF. The trap is the same one that catches people on SMD resistors: 220 means 22 pF, not 220 pF, because the last digit is a multiplier, not a figure. Below 10 pF the code is not used at all and the value is printed plainly, so a part marked “22” with nothing else is 22 pF. For the tolerance and voltage letters that go with the code — the J, K and M and the 1H, 2A and so on — use the capacitor code calculator, which decodes the whole marking.
Two older conventions that still bite. Some schematics, especially older American ones, write “mfd” or even “mF” where they mean microfarads, and “mmfd” or “µµF” where they mean picofarads. If a value looks a million times too large or too small for what it is doing, that is usually why. This page uses mF strictly as the SI millifarad, so a 4,700 µF reservoir capacitor reads as 4.7 mF.
The value on the part is nominal. Capacitors come in the E6 and E12 series rather than E24, which is why 10, 22, 47 and 100 keep appearing, and their tolerances are wide — ±10% or ±20% is normal for a ceramic, and Y5V dielectrics are specified −20/+80%. Worse, a high-K ceramic loses capacitance as you apply voltage to it: an X7R rated 100 nF at 16 V may be nearer half that with 12 V across it. Electrolytics drift with age and temperature. If the value matters — a filter corner, an oscillator frequency — use a C0G/NP0 or film part and check the tolerance.
What a capacitance actually does depends on the frequency: 100 nF is 1.592 kΩ at 1 kHz and about a thousandth of that at 1 MHz. The reactance calculator works that out at any frequency, the RC time constant calculator gives the charging time with a resistor, and the LC resonant frequency calculator uses it with an inductor to set a frequency.
Frequently asked questions
How many nF are in a µF?
A thousand. 1 µF = 1,000 nF = 1,000,000 pF, and 1,000 µF = 1 mF.
What is 100 nF in µF?
0.1 µF — the same part, and also 100,000 pF, and marked 104 on its body. It is the standard decoupling capacitor.
What does 104 mean on a capacitor?
10 followed by four zeros, in picofarads: 100,000 pF, which is 100 nF or 0.1 µF.
Is a capacitor marked 220 equal to 220 pF?
No — it is 22 pF. The last digit is the number of zeros to add, and zero zeros means ×1. A 220 pF part is marked 221.
What does mfd mean on an old capacitor?
Microfarads. Older schematics and motor capacitors use mfd, MFD or even mF for the microfarad, and mmfd or µµF for the picofarad. In SI, mF is the millifarad, a thousand times bigger.
What is 4,700 µF in farads?
0.0047 F, or 4.7 mF. Reservoir capacitors are almost always quoted in microfarads however large they get.
Related calculators
References
- IEC 60062:2016. Marking codes for resistors and capacitors, edition 6.0: the R (and K, M) decimal-point notation and the three-digit capacitor code. International Electrotechnical Commission.
- IEC 60063:2015. Preferred number series for resistors and capacitors (the E6, E12, E24, E48, E96 and E192 series). International Electrotechnical Commission.
- Horowitz P, Hill W. The Art of Electronics, 3rd ed. Cambridge University Press, 2015. Chapter 1 (resistors in series and parallel, reactance, resonance, zener regulators) and Chapter 9 (voltage regulators).