333 capacitor value
33 nF
33,000 pF · 33 nF · 0.033 µF
| Marked code | 333 |
| Picofarads | 33,000 pF |
| Nanofarads | 33 nF |
| Microfarads | 0.033 µF |
| Farads | 3.30e-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:
33 × 103 = 33,000 pF
So 333 is 33 followed by 3 zeros: 33,000 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 333 is stocked as 0.033 µF and the two numbers look nothing alike.
What 33 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 33 nF part covers several orders of magnitude:
| Frequency | Reactance |
|---|---|
| 50 Hz — mains | 96.46 kΩ |
| 1 kHz — audio | 4.82 kΩ |
| 100 kHz — switching | 48.23 Ω |
| 10 MHz — RF | 482.3 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 333K carries a tolerance letter. It is not part of the value:
| Letter | Tolerance | 33 nF means |
|---|---|---|
333J | ±5% | 31.35 nF to 34.65 nF |
333K | ±10% | 29.7 nF to 36.3 nF |
333M | ±20% | 26.4 nF to 39.6 nF |
333Z | +80% / −20% | 26.4 nF to 59.4 nF |
A Z is worth knowing about. +80%/−20% is a real tolerance on cheap high-permittivity ceramics, and it means a part marked 333Z can legitimately be anything from 26.4 nF to 59.4 nF. Those go in decoupling positions where only the rough size matters, never in a timing or filter position.
Where 33 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 333 capacitor?
33 nF — 33,000 pF · 33 nF · 0.033 µF. The first two digits are the value in picofarads and the third is how many zeros follow, so 333 is 33 followed by 3 zeros = 33,000 pF.
What is a 333 capacitor in µF?
0.033 µF. Going from picofarads to microfarads is six decimal places, which is where most of the confusion with these codes comes from — 33,000 pF, 33 nF and 0.033 µF are the same capacitor written three ways.
What does the letter after 333 mean?
Tolerance. 333K is ±10%, 333J is ±5% and 333M is ±20% — so a 333K is anywhere from 29.7 nF to 36.3 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 333 capacitor at 1 kHz?
4.82 kΩ. Reactance is 1 ÷ (2πfC), so it falls as the frequency rises: the same part is 48.23 Ω at 100 kHz and 482.3 mΩ at 10 MHz.
Nearby codes
- 393 capacitor — 39 nF
- 473 capacitor — 47 nF
- 563 capacitor — 56 nF
- 683 capacitor — 68 nF
- 823 capacitor — 82 nF
- 104 capacitor — 100 nF
- 124 capacitor — 120 nF
- 154 capacitor — 150 nF
- 184 capacitor — 180 nF
- 224 capacitor — 220 nF