Decoding Capacitor Part Markings
This guide will take the mystery out of identifying part markings on the various styles of surface mount chip style capacitors.
Surface Mount Chip Capacitors
These utilize methods to mark capacitors too small to have the information presented outright. Your capacitor will have markings two to four characters is length. That length and how they are arranged will play a part in decoding.
Standard-tolerance SMD capacitors use a 3-digit code to mark the capacitance value on the part. The first two numbers will indicate the significant digits, and the third will be the multiplier. ‘R’ is used to indicate the position of a decimal point.
To get our value we multiply our significant digits against our multiplier. We simply add that number of zeros on to the end. This value is in picofarads. To change to to microfarads, simply move the decimal point to the left six spaces.
10 + 0,000,000 = 100,000,000pf
100,000,000 pf = 100µF
Similar to the three digit EIA, the four digit format uses the beginning values to indicate the significant digits, the last digit as the multiplier and a letter designating a tolerance. ‘R’ is used to indicate the position of a decimal point. The four digit format allows for higher precision.
Tolerance Value in %
The Tolerance code D = 0.5%
Two-Digit EIA ( EIA-198)
Sometimes there is so little room on the part that even the standards are not practical. The EIA-198 system of part marking uses two characters (one number and one letter) in which the letter represents the value and number represents the multiplier. There are a couple of things to know.
This system is case sensitive.
You will notice that by using some of the lower-case versions of letters they could eliminate many of the troublesome numbers such as I and O. They too easily get confused for 1 and 0.
The capacitance codes are not based upon the capacitance value like the others
The first digit is used for capacitance and correlate to the following tables.
, While this system is still measured in picofarads, The multiplier code is one more than what we are used to in the other two methods. Please be aware
If you would rather do some pointing and clicking to find your value I recommend you check out our SMD Capacitor Code Calculator.
Quick links to other capacitor related topics you may find helpful.
Part Selection and Part Markings
One questions that comes through our department is from customers who are trying to identify a surface mount Aluminum Electrolytic Cap and there is no Voltage listed. Once we start looking at the cap we often find that the voltage is listed, however as a letter and not the actual voltage value.
Here is a marking chart from
Rubycon’s TZV series of Capacitors.
Cornell Dubilier has a similar chart with their AFK Series
This however is not standard as some of the capacito…
The table below provides a brief summary of different capacitor types and their relative merits, arranged approximately in terms of decreasing quantity (or increasing quality) of capacitance offered by each type.
Approx. value range
C*V product range
Disadvantages/things to beware of
Electric double layer, Supercaps
6.8mF to 4000F
2.1 to 75v
.03 to 10,000
Exceptionally high C/V ratio. Possible alternative to…
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There are a lot of capacitors that use the marking MFD or mFd after the capacitance value.
This marking most often on capacitors is actually the same as µF. The µF stands for microFarad.
It was common practice on older capacitors to be marked as MFD or mFd either for machinery difficulty to produce the µ symbol print on the casing or for other manufacturer specific reasons.
Here is an example of a capacitor that is still active - The product is listed as 330 uF per our
product page and als…
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