823 capacitor value
82 nF
82,000 pF · 82 nF · 0.082 µF
| Marked code | 823 |
| Picofarads | 82,000 pF |
| Nanofarads | 82 nF |
| Microfarads | 0.082 µF |
| Farads | 8.20e-8 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 × 103 = 82,000 pF
So 823 is 82 followed by 3 zeros: 82,000 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 823 is stocked as 0.082 µF and the two numbers look nothing alike.
What 82 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 82 nF part covers several orders of magnitude:
| Frequency | Reactance |
|---|---|
| 50 Hz — mains | 38.82 kΩ |
| 1 kHz — audio | 1.94 kΩ |
| 100 kHz — switching | 19.41 Ω |
| 10 MHz — RF | 194.1 mΩ |
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 823K carries a tolerance letter. It is not part of the value:
| Letter | Tolerance | 82 nF means |
|---|---|---|
823J | ±5% | 77.9 nF to 86.1 nF |
823K | ±10% | 73.8 nF to 90.2 nF |
823M | ±20% | 65.6 nF to 98.4 nF |
823Z | +80% / −20% | 65.6 nF to 147.6 nF |
A Z is worth knowing about. +80%/−20% is a real tolerance on cheap high-permittivity ceramics, and it means a part marked 823Z can legitimately be anything from 65.6 nF to 147.6 nF. Those go in decoupling positions where only the rough size matters, never in a timing or filter position.
Where 82 nF turns up
Tens of nanofarads is coupling between audio stages and the smaller decoupling capacitors on a logic board. A 10 nF part alongside a 100 nF one is a common pairing, the smaller of the two handling the frequencies the larger one is too slow for.
Frequently asked questions
What is the value of a 823 capacitor?
82 nF — 82,000 pF · 82 nF · 0.082 µF. The first two digits are the value in picofarads and the third is how many zeros follow, so 823 is 82 followed by 3 zeros = 82,000 pF.
What is a 823 capacitor in µF?
0.082 µF. Going from picofarads to microfarads is six decimal places, which is where most of the confusion with these codes comes from — 82,000 pF, 82 nF and 0.082 µF are the same capacitor written three ways.
What does the letter after 823 mean?
Tolerance. 823K is ±10%, 823J is ±5% and 823M is ±20% — so a 823K is anywhere from 73.8 nF to 90.2 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 823 capacitor at 1 kHz?
1.94 kΩ. Reactance is 1 ÷ (2πfC), so it falls as the frequency rises: the same part is 19.41 Ω at 100 kHz and 194.1 mΩ at 10 MHz.
Nearby codes
- 104 capacitor — 100 nF
- 124 capacitor — 120 nF
- 154 capacitor — 150 nF
- 184 capacitor — 180 nF
- 224 capacitor — 220 nF
- 274 capacitor — 270 nF
- 334 capacitor — 330 nF
- 394 capacitor — 390 nF
- 474 capacitor — 470 nF
- 564 capacitor — 560 nF