566 capacitor value
56 µF
56,000,000 pF · 56000 nF · 56 µF
| Marked code | 566 |
| Picofarads | 56,000,000 pF |
| Nanofarads | 56000 nF |
| Microfarads | 56 µF |
| Farads | 5.60e-5 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:
56 × 106 = 56,000,000 pF
So 566 is 56 followed by 6 zeros: 56,000,000 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 566 is stocked as 56 µF and the two numbers look nothing alike.
What 56 µF 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 56 µF part covers several orders of magnitude:
| Frequency | Reactance |
|---|---|
| 50 Hz — mains | 56.84 Ω |
| 1 kHz — audio | 2.84 Ω |
| 100 kHz — switching | 28.4 mΩ |
| 10 MHz — RF | 0.3 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 566K carries a tolerance letter. It is not part of the value:
| Letter | Tolerance | 56 µF means |
|---|---|---|
566J | ±5% | 53.2 µF to 58.8 µF |
566K | ±10% | 50.4 µF to 61.6 µF |
566M | ±20% | 44.8 µF to 67.2 µF |
566Z | +80% / −20% | 44.8 µF to 100.8 µF |
A Z is worth knowing about. +80%/−20% is a real tolerance on cheap high-permittivity ceramics, and it means a part marked 566Z can legitimately be anything from 44.8 µF to 100.8 µF. Those go in decoupling positions where only the rough size matters, never in a timing or filter position.
Where 56 µF turns up
Microfarads and up is bulk energy storage: holding a rail up between switching cycles, smoothing a supply, or coupling a signal that goes down to a few hertz. Above about 10 µF ceramics give way to electrolytics and tantalums, which is why the code runs out here.
Frequently asked questions
What is the value of a 566 capacitor?
56 µF — 56,000,000 pF · 56000 nF · 56 µF. The first two digits are the value in picofarads and the third is how many zeros follow, so 566 is 56 followed by 6 zeros = 56,000,000 pF.
What is a 566 capacitor in µF?
56 µF. Going from picofarads to microfarads is six decimal places, which is where most of the confusion with these codes comes from — 56,000,000 pF, 56000 nF and 56 µF are the same capacitor written three ways.
What does the letter after 566 mean?
Tolerance. 566K is ±10%, 566J is ±5% and 566M is ±20% — so a 566K is anywhere from 50.4 µF to 61.6 µF 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 566 capacitor at 1 kHz?
2.84 Ω. Reactance is 1 ÷ (2πfC), so it falls as the frequency rises: the same part is 28.4 mΩ at 100 kHz and 0.3 mΩ at 10 MHz.
Nearby codes
- 686 capacitor — 68 µF
- 826 capacitor — 82 µF
- 108 capacitor — 0.1 pF
- 128 capacitor — 0.12 pF
- 158 capacitor — 0.15 pF
- 188 capacitor — 0.18 pF
- 228 capacitor — 0.22 pF
- 278 capacitor — 0.27 pF
- 338 capacitor — 0.33 pF
- 398 capacitor — 0.39 pF