In this instructible, I will try to explain the markings on capacitors and how to determine the values.  Firstly, there are a few different styles of capacitor packages.  The can style, flat disc and bead styles.  The can styles are large enough to have the values printed on the sides and usually range from 1uF (micro farads) upwards.  As with smaller disc capacitors, the capacitance is usually smaller than 1uf and go into pF (pico farads)  When determining the capacitance of these disc style capacitors, they have numbers printed onto one face, these numbers are read similar to reading resistor values, where the first two numbers are the significant numbers and the third number is the multiplier (number of zero's to add to the value). For example the pictures I have included. 821 would be 820pF, 331 is 330pF, 582 is 5800pF (0.0058uF) and 472 is 4700pF (0.0047uF). Other letters relate to tolerances and teperature ranges etc.

To help clarify the relation beween micro and pico farads 1 pF is equivalent to 0.000001 uF
Or the other way round it is 1 uF is equivalent to 1000000 pF

I have tried to explain as best as possible how I have come to learn these quite small values, and how micro and pico are related.  When I first started out in electronics, this was all nonsense to me until I got a few books from the local library and taught myself.
yemshog10 months ago

hi please i want to know how to build phone charger

i know i have to have a transformer, capacitor , a resistor and BRD

but i dont know how everything will work together how to determine which value will work together. but the charger will be 12v

danny591 year ago
You did a good job of explaining these numbers. I have also been teaching myself electronics, either from books or visiting such sites as this. There are some very smart people out in the world and you can really learn a lot from them.
pussiedoctor (author)  danny591 year ago
Thankyou. When I was learning to read these capacitors, I was amazed that the values were so small.
Hi, i saw a green colored capacitor with the printed value 682K100 can you tell me how to get it's capacitance?