Capacitor Code Calculator — 104 means 100 nF
Decode 3-digit ceramic capacitor codes, tolerance letters and voltage codes. 104 means 100 nF — this explains why.
Example: Capacitor code 104 is 100 nF — that is 100000 pF.
Formula
C = AB × 10^C picofaradsWorked example
Capacitor code 104 is 100 nF — that is 100000 pF.
C = digits × 10^exponent (picofarads)
10 × 10^4 pF — the third digit is the number of zeros, and the base unit is picofarads.
C = 100 nF
Frequently asked questions
What does 104 mean on a capacitor?
100 nF, also written 0.1 µF. The first two digits are significant figures and the third is the number of zeros, all in picofarads — so 104 is 10 followed by four zeros, 100,000 pF. Divide by 1,000 for nF and by 1,000,000 for µF.
Why are capacitor codes in picofarads when nobody buys picofarads?
Because it lets the whole practical range be written with three digits and no decimal point or unit, which is all that fits on a small ceramic part. It is a printing constraint, not a design choice, and it is exactly why the code is confusing.
What does the letter after the code mean?
Tolerance. J is ±5%, K is ±10%, M is ±20%. Small-value parts use absolute letters instead: B is ±0.1 pF, C is ±0.25 pF. Z is the unusual one — +80%/−20%, common on cheap bulk decoupling.
Does the code tell me the voltage rating or dielectric?
No, and both matter more than the tolerance. An X7R or Y5V capacitor can lose a large fraction of its rated capacitance under DC bias and across temperature — a 10 µF X5R at its rated voltage may measure closer to 3 µF. For timing, filters and anything precise, use C0G/NP0 and check the datasheet.
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