A guide to read capacitor mark

Capacitors are fundamental components in electrical circuits, symbolized in diagrams by parallel lines representing the plates and a gap signifying the dielectric between them.

The "U" symbol on a capacitor denotes its voltage rating, indicating the maximum voltage it can withstand safely without damage. For instance, a marking such as "U = 25V" means the capacitor can handle a maximum of 25 volts.

  So how do we read a capacitor mark?

Capacitors have markings representing their key specifications. Capacitance, measured in Farads or commonly in microfarads (μF), nanofarads (nF), or picofarads (pF), is denoted by numerical codes such as "104" representing 0.1 μF. Tolerance, indicating the allowable deviation from the stated capacitance, might be marked as "K" for ± 10% or "M" for ± 20%. Additionally, the voltage rating, represented as "U" or "V," signifies the maximum voltage the capacitor can handle safely.

Example I:

Marking: 473J 

The numeric code "473" on this capacitor indicates a capacitance value of 47 with 3 zeros in picofarads, translating to 47,000 pF or 47 nF. Accompanying this, the letter "J" signifies a tolerance level of ± 5%.

Example II:

Marking: 105K

On this capacitor, the numerical code "105" stands for 10 with 5 zeros in picofarads, equivalent to 1,000,000 pF or 1 μF. Correspondingly, the letter "K" denotes a tolerance of ± 10%.

  Summarization

When reading a capacitor mark, you interpret the numerical code for capacitance, the letter code for tolerance, and the voltage rating to understand its specifications. It's important to note that capacitor markings might vary depending on the manufacturer and capacitor type, so referring to datasheets or manufacturer specifications for precise details is advisable.