Capacitor Code Calculator

How to use the capacitor code calculator

1. Fill in the fields — they start with a worked example.
2. Read the answer, and the arithmetic shown beneath it.
3. Copy the results, or adjust the inputs to compare scenarios.

About this tool

Small ceramic capacitors are marked with a three-digit code rather than a value, for the same reason resistors use colours: there is no room to print the real number. The first two digits are significant figures and the third is how many zeros follow, giving a result in picofarads.

So the ubiquitous <strong>104</strong> is 10 followed by four zeros — 100,000 pF, which is 100 nF, which is 0.1 µF. All three describe the same part, and which unit gets used depends entirely on where you are reading: schematics tend to say 0.1 µF, parts catalogues say 100 nF.

That unit confusion causes more mistakes than the code itself. A capacitor marked 104 is not 104 pF, and 100 nF is not a thousand times different from 0.1 µF — it is the same thing.

Codes below 100 are usually the value in picofarads directly, so a part marked 47 is simply 47 pF rather than 47 followed by nothing.

Common uses

• Identifying a ceramic capacitor from a parts drawer.
• Checking a 104 is the 100 nF the schematic asked for.
• Converting between pF, nF and µF.

Frequently asked questions

What value is a capacitor marked 104?

100 nF — that is 100,000 pF or 0.1 µF. All three are the same part, described in different units.

Is a code of 47 the same as 470?

No. 47 is 47 pF directly, while 470 means 47 followed by one zero, which is 470 pF. Two-digit codes are read literally.

What does the letter after the code mean?

Tolerance. J is ±5%, K is ±10% and M is ±20%. It is separate from the value itself.