Ceramic and film capacitors are marked with a short code instead of the value. Type it here, such as 104, 473J or 4n7, and you get the capacitance in picofarads, nanofarads and microfarads, plus the tolerance if there's a letter.
Or type a value (100n, 0.1 µF, 4.7 nF) to see which code to look for when you buy or replace a part.
How to use
- Type the code as printed. The letter at the end (J, K, M…) is the tolerance; a number on a second line is usually the voltage.
- Read the value in all three units: 100 nF and 0.1 µF are the same capacitor.
- To find the code for a value, type it in the second box and pick the unit.
- When replacing a capacitor, keep the same capacitance and use a voltage rating that's the same or higher.
How to read a capacitor code
The first two digits are the value and the third is the number of zeros, always in picofarads. 104 is 10 plus four zeros: 100,000 pF, which is 100 nF or 0.1 µF. 222 is 2,200 pF, or 2.2 nF. When the third digit is 8 or 9, it multiplies by 0.01 or 0.1: 479 is 4.7 pF.
Letter codes and tolerance
Codes like 4n7, n47 or 2u2 use the unit letter as the decimal point: 4.7 nF, 0.47 nF and 2.2 µF. Tolerance letters: F ±1%, G ±2%, J ±5%, K ±10%, M ±20% and Z +80%/−20%. Below 10 pF, B, C and D mean ±0.1, ±0.25 and ±0.5 pF.
Electrolytic capacitors
Electrolytic capacitors are big enough to have the value printed in full, like 100 µF 25 V. The stripe with minus signs marks the negative lead: fitted backwards, an electrolytic can bulge or burst.