103 capacitor value
10 nF
10,000 pF · 10 nF · 0.01 µF
| Marked code | 103 |
| Picofarads | 10,000 pF |
| Nanofarads | 10 nF |
| Microfarads | 0.01 µF |
| Farads | 1.00e-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:
10 × 103 = 10,000 pF
So 103 is 10 followed by 3 zeros: 10,000 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 103 is stocked as 0.01 µF and the two numbers look nothing alike.
What 10 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 10 nF part covers several orders of magnitude:
| Frequency | Reactance |
|---|---|
| 50 Hz — mains | 318.31 kΩ |
| 1 kHz — audio | 15.92 kΩ |
| 100 kHz — switching | 159.15 Ω |
| 10 MHz — RF | 1.59 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 103K carries a tolerance letter. It is not part of the value:
| Letter | Tolerance | 10 nF means |
|---|---|---|
103J | ±5% | 9.5 nF to 10.5 nF |
103K | ±10% | 9 nF to 11 nF |
103M | ±20% | 8 nF to 12 nF |
103Z | +80% / −20% | 8 nF to 18 nF |
A Z is worth knowing about. +80%/−20% is a real tolerance on cheap high-permittivity ceramics, and it means a part marked 103Z can legitimately be anything from 8 nF to 18 nF. Those go in decoupling positions where only the rough size matters, never in a timing or filter position.
Where 10 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 103 capacitor?
10 nF — 10,000 pF · 10 nF · 0.01 µF. The first two digits are the value in picofarads and the third is how many zeros follow, so 103 is 10 followed by 3 zeros = 10,000 pF.
What is a 103 capacitor in µF?
0.01 µF. Going from picofarads to microfarads is six decimal places, which is where most of the confusion with these codes comes from — 10,000 pF, 10 nF and 0.01 µF are the same capacitor written three ways.
What does the letter after 103 mean?
Tolerance. 103K is ±10%, 103J is ±5% and 103M is ±20% — so a 103K is anywhere from 9 nF to 11 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 103 capacitor at 1 kHz?
15.92 kΩ. Reactance is 1 ÷ (2πfC), so it falls as the frequency rises: the same part is 159.15 Ω at 100 kHz and 1.59 Ω at 10 MHz.
Nearby codes
- 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
- 683 capacitor — 68 nF