Capacitor Code Calculator

In short A three-digit code on a ceramic capacitor works exactly like a resistor's colour bands: the first two digits are the value and the third says how many zeros to add — always in picofarads. So 104 is 10 followed by four zeros, which is 100,000 pF, which is 100 nF, which is 0.1 µF. Those are the same capacitor written three ways, and which one you hear depends on who is talking; 104 is the standard decoupling capacitor that sits beside almost every integrated circuit. The trap is a code whose third digit is 0. 470 is not 470 pF — it is 47 followed by no zeros, so 47 pF. Anyone reading it as a plain number is out by a factor of ten. A letter after the digits is the tolerance: J is ±5%, K is ±10%, M is ±20% and Z is the notoriously loose −20% to +80%. Markings that already contain a letter inside the number are not codes at all. 4n7 means 4.7 nF and 2µ2 means 2.2 µF, with the unit letter standing in for the decimal point — a European convention that avoids a decimal point disappearing on a bad photocopy. Only a bare three-digit number is a multiplier code. Finally, treat ceramic values loosely: capacitance falls with applied voltage and with age, so a nominally 10% part can be well outside that in a working circuit. Where the value matters, use film and read the datasheet.