822 capacitor value
8.2 nF
8,200 pF · 8.2 nF · 0.0082 µF
| Marked code | 822 |
| Picofarads | 8,200 pF |
| Nanofarads | 8.2 nF |
| Microfarads | 0.0082 µF |
| Farads | 8.20e-9 F |
Reading the code
The three digits are not a part number. The first two are the value in picofarads and the third says what to do with them:
82 × 102 = 8,200 pF
So 822 is 82 followed by 2 zeros: 8,200 pF. The code is always in picofarads even when the part is sold in microfarads, which is the whole difficulty with it — a capacitor marked 822 is stocked as 0.0082 µF and the two numbers look nothing alike.
What 8.2 nF does at frequency
A capacitor's opposition to a signal is its reactance, 1 ÷ (2πfC), and it falls as the frequency rises. Over the range of frequencies a circuit can put across it, a 8.2 nF part covers several orders of magnitude:
| Frequency | Reactance |
|---|---|
| 50 Hz — mains | 388.18 kΩ |
| 1 kHz — audio | 19.41 kΩ |
| 100 kHz — switching | 194.09 Ω |
| 10 MHz — RF | 1.94 Ω |
Ten times the frequency is a tenth of the reactance, every time — which is why choosing a decoupling capacitor is really choosing the frequency band you want it to be low-impedance across, and why boards carry several sizes in parallel rather than one large one.
The letter after the number
A code like 822K carries a tolerance letter. It is not part of the value:
| Letter | Tolerance | 8.2 nF means |
|---|---|---|
822J | ±5% | 7.79 nF to 8.61 nF |
822K | ±10% | 7.38 nF to 9.02 nF |
822M | ±20% | 6.56 nF to 9.84 nF |
822Z | +80% / −20% | 6.56 nF to 14.76 nF |
A Z is worth knowing about. +80%/−20% is a real tolerance on cheap high-permittivity ceramics, and it means a part marked 822Z can legitimately be anything from 6.56 nF to 14.76 nF. Those go in decoupling positions where only the rough size matters, never in a timing or filter position.
Where 8.2 nF turns up
Single-figure nanofarads is audio filtering and snubbing across switch contacts. It is also the range where a capacitor stops being a precision component and starts being a bypass, depending on the dielectric it is made from.
Frequently asked questions
What is the value of a 822 capacitor?
8.2 nF — 8,200 pF · 8.2 nF · 0.0082 µF. The first two digits are the value in picofarads and the third is how many zeros follow, so 822 is 82 followed by 2 zeros = 8,200 pF.
What is a 822 capacitor in µF?
0.0082 µF. Going from picofarads to microfarads is six decimal places, which is where most of the confusion with these codes comes from — 8,200 pF, 8.2 nF and 0.0082 µF are the same capacitor written three ways.
What does the letter after 822 mean?
Tolerance. 822K is ±10%, 822J is ±5% and 822M is ±20% — so a 822K is anywhere from 7.38 nF to 9.02 nF and still in specification. A Z means +80%/−20%, which is not a mistake: some ceramic dielectrics really are that loose.
What is the impedance of a 822 capacitor at 1 kHz?
19.41 kΩ. Reactance is 1 ÷ (2πfC), so it falls as the frequency rises: the same part is 194.09 Ω at 100 kHz and 1.94 Ω at 10 MHz.
Nearby codes
- 103 capacitor — 10 nF
- 123 capacitor — 12 nF
- 153 capacitor — 15 nF
- 183 capacitor — 18 nF
- 223 capacitor — 22 nF
- 273 capacitor — 27 nF
- 333 capacitor — 33 nF
- 393 capacitor — 39 nF
- 473 capacitor — 47 nF
- 563 capacitor — 56 nF