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Capacitor Code Calculator

Small ceramic and film capacitors print a 3-digit code that gives the value in picofarads. The first two digits are the number and the third is how many zeros to add: 104 is 10 followed by four zeros, 100 000 pF, which is 100 nF or 0.1 µF. A letter after the code is the tolerance.

Result

Capacitance of 104

100 nF

In picofarads: 100 000 pF
In nanofarads: 100 nF
In microfarads: 0.1 µF
How it reads: 10 × 10000 pF (the last digit, 4, is the number of zeros to add)

Add the tolerance letter that follows the digits (104K) to see the range.

The formula

The value from a 3-digit code

\htmlData{sym=C}{C} = \htmlData{sym=N:code}{N} \times 10^{\htmlData{sym=K:last}{K}}\ \htmlData{funit=pF}{\text{pF}}

What each letter means

$C$: Capacitance (F · farad) : How much charge a capacitor stores per volt.
$N$: Number from the first digits (no unit) : The digits of the code before the last one, read as one number (the 10 in 103).
$K$: Last digit of the code (no unit) : The number of zeros to add (the 3 in 103). On capacitors, 8 means × 0.01 and 9 means × 0.1.

How it works

Write the first two digits, then add as many zeros as the third digit says. 104 is 10 and four zeros: 100 000 pF. 472 is 47 and two zeros: 4700 pF, which is 4.7 nF. 105 is 1 000 000 pF, or 1 µF. One picofarad is a millionth of a microfarad, so move the decimal point three places to go from pF to nF and three more to go to µF.

A third digit of 9 does not mean nine zeros. It means × 0.1, which is how values below 10 pF are written: 229 is 22 × 0.1 = 2.2 pF. A third digit of 8 means × 0.01. Some small parts print just the value, with a prefix as the decimal point (4n7 is 4.7 nF, 2p2 is 2.2 pF), and the calculator reads those too.

The letter after the digits is the tolerance. B is ±0.1 pF, C ±0.25 pF, D ±0.5 pF (or ±0.5 % on bigger values), F ±1 % (or ±1 pF on small ones), G ±2 %, J ±5 %, K ±10 %, M ±20 % and Z is −20 % to +80 %. A K or M ceramic capacitor can be well off its marked value, which is fine for decoupling but not for timing circuits. Standard values come from the E6, E12 and E24 series: 1.0, 1.5, 2.2, 3.3, 4.7 and 6.8 are the common ones.

Worked example

104: 10 followed by four zeros is 100 000 pF. That is 100 nF, or 0.1 µF.
472: 47 followed by two zeros is 4700 pF, which is 4.7 nF.
229: the last digit 9 means × 0.1, so 22 × 0.1 = 2.2 pF, which is 0.0022 nF.
104K: the letter K is ±10 %, so the real value of a 100 nF part lies between 90 nF and 110 nF.
The other way: 100 nF is 100 000 pF, which is 10 followed by four zeros, so the code is 104. Add the tolerance letter J (±5 %) and the part is marked 104J.

Common questions

Is the code in pF, nF or µF?

Always picofarads. This is the one thing to remember: 104 is 100 000 pF, not 104 µF. Divide by 1000 for nF and by 1 000 000 for µF.

What does the letter after the code mean?

It is the tolerance, how far from the marked value the real capacitance may be. J is ±5 %, K ±10 % and M ±20 %. Do not confuse it with the voltage code (a digit and a letter, such as 1H) that some makers print as well.

Why is there no code on my electrolytic capacitor?

Larger capacitors have room to print the value in full, such as 100 µF 25 V. The 3-digit code is for small ceramic and film parts. Remember that an electrolytic has a positive and a negative lead, while a coded ceramic or film capacitor does not.

Try it live

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