How To Read Capacitor Value?

Capacitor Standard Codes

Generally, the values of capacitance, voltage rating, tolerance and even the polarity (in case of polarized capacitor) are printed on the large size capacitor. On the other hand, for small capacitors like mica and ceramic capacitors, color codes are used to indicate their values (generally) in pF (picofarad).

The value of ceramic disk capacitors lower than 1000pf is printed on it in the form of digits and numbers. For example, the only number “300” is printed on a capacitor of 300pf.

Those capacitors having capacitance of 1000pf or more, their values can be read by the 3 digits numbers (e.g. 102. 103, 105 etc.) printed on it. These 3 digits color coding can be read as follows.

• 102 = 10 x 10² = 1000 pF (picofarad)
• 103 = 10 x 10³ = 10,000 pF (picofarad)
• 105 = 10 x 10⁵ = 1,000,000. pF (picofarad) = 1 μF (microfarad)

Reading Value of Large Cylindrical Capacitors (Polarized & Non-Polarized)

Generally, the overall rating is written and printed on these capacitors. For example

The fig 1

• The value of capacitance is 47 μF (microfarad).
• The value of maximum voltage this capacitor bears is 400V DC

The fig 1 (c)

• The value of capacitance is 1200 nF (nanofarad).
• The value of maximum bearable voltage is 500V.
• The value of tolerance is ± 5%. e.g. variation of capacitance in plus minus.

The fig 1 (c)

• The value of capacitance is 1200 μF (microfarad).
• The value of maximum voltage is 63 V DC.
• The value of tolerance is ± 20%.
• The value of temperature coefficient is -40 to +105°C.

The fig 1 (d)

We will show a solved example and table (see fig 3) below to show how to read the value of ceramic capacitors

• The value of capacitance is 0.01 μF (microfarad).
• The value of maximum voltage is “2G” (400V).
• The value of tolerance is “J” ± 5%.

fig 1

Keep in mind that polarized and non-polarized capacitors as well as AC and DC capacitors can only be used according to the specifications. For example, A DC capacitor can’t be operated at AC supply and vice versa until and unless mentioned in the user Manual. The VDC and VAC are mentioned on the capacitor rating nameplate with negative (-) sign for negative terminal on it.

The following symbols and units are used to represent the values of capacitance of capacitors in  Microfarad (μF), Nano-farad (nF) & Picofarad (pF).