182 capacitor value
1.8 nF
1,800 pF · 1.8 nF · 0.0018 µF
| Marked code | 182 |
| Picofarads | 1,800 pF |
| Nanofarads | 1.8 nF |
| Microfarads | 0.0018 µF |
| Farads | 1.80e-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:
18 × 102 = 1,800 pF
So 182 is 18 followed by 2 zeros: 1,800 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 182 is stocked as 0.0018 µF and the two numbers look nothing alike.
What 1.8 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 1.8 nF part covers several orders of magnitude:
| Frequency | Reactance |
|---|---|
| 50 Hz — mains | 1.77 MΩ |
| 1 kHz — audio | 88.42 kΩ |
| 100 kHz — switching | 884.19 Ω |
| 10 MHz — RF | 8.84 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 182K carries a tolerance letter. It is not part of the value:
| Letter | Tolerance | 1.8 nF means |
|---|---|---|
182J | ±5% | 1.71 nF to 1.89 nF |
182K | ±10% | 1.62 nF to 1.98 nF |
182M | ±20% | 1.44 nF to 2.16 nF |
182Z | +80% / −20% | 1.44 nF to 3.24 nF |
A Z is worth knowing about. +80%/−20% is a real tolerance on cheap high-permittivity ceramics, and it means a part marked 182Z can legitimately be anything from 1.44 nF to 3.24 nF. Those go in decoupling positions where only the rough size matters, never in a timing or filter position.
Where 1.8 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 182 capacitor?
1.8 nF — 1,800 pF · 1.8 nF · 0.0018 µF. The first two digits are the value in picofarads and the third is how many zeros follow, so 182 is 18 followed by 2 zeros = 1,800 pF.
What is a 182 capacitor in µF?
0.0018 µF. Going from picofarads to microfarads is six decimal places, which is where most of the confusion with these codes comes from — 1,800 pF, 1.8 nF and 0.0018 µF are the same capacitor written three ways.
What does the letter after 182 mean?
Tolerance. 182K is ±10%, 182J is ±5% and 182M is ±20% — so a 182K is anywhere from 1.62 nF to 1.98 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 182 capacitor at 1 kHz?
88.42 kΩ. Reactance is 1 ÷ (2πfC), so it falls as the frequency rises: the same part is 884.19 Ω at 100 kHz and 8.84 Ω at 10 MHz.
Nearby codes
- 222 capacitor — 2.2 nF
- 272 capacitor — 2.7 nF
- 332 capacitor — 3.3 nF
- 392 capacitor — 3.9 nF
- 472 capacitor — 4.7 nF
- 562 capacitor — 5.6 nF
- 682 capacitor — 6.8 nF
- 822 capacitor — 8.2 nF
- 103 capacitor — 10 nF
- 123 capacitor — 12 nF