Capacitor codes and conversions

As small general purpose capacitors values range from a few pF to less than 1 µF the convention arose that whole numbers designate values in picofarads while decimal fractions designates values in microfarads. Any capacitor with a value of 1 µF or above is large enough to be marked with its actual value. A newer way to mark values is with three numbers on the body of the capacitor with the value in picofarads. The first two digits are the significant figures and the third the multiplier (i.e. number of zeros). So for example 151 indicates a capacitance of 150 pF.

Often p, n and u are substituted for the decimal point. For example 8p2 for 8.2pF, n51 for 0.51nF or 4u7 for 4.7µF.