Large capacitors (generally electrolyte capacitors) generally have value printed on them like 470uF 16 V, 220uF 25V and something like that. But if you have a small capacitor, then you might freak. Not to worry! They are as simple to read as others. Small capacitors normally have 3 digits printed on them, and a few have 2 digits printed and the readings are almost always in Pico-Farads, unless it is specifically mentioned as n (nano) or µ (micro). Suppose if a capacitor has numbers 22 printed on them, then it means the value of the capacitor is 22 Pico-farads (PF). If there is a third number, then it is considered to be a multiplier, or just number of zeros after the value.
Suppose you have a small ceramic capacitor marked as 103, then the capacitance is 10 x 10^3 = 10000pF, which is nothing but 0.01 µF (micro-farad).. Be cautious if the last digit is 8 or 9 which signifies 0.01 and 0.1 respectively as a multiplying factor. If you have read resistor tutorial, then you already know this concept
This information is more than enough to decode most of the capacitors. However, manufactures are more nerds and tend to confuse us by adding an alphabet after the numbers. This denotes nothing more than tolerance of the capacitor.
|Alphabet||Tolerance in pF - Actual Value|
|B||+ / - 0.10pF|
|C||+ / - 0.25pF|
|D||+ / - 0.50pF|
|Alphabet||Tolerance in pF - Value in percentage|
Suppose you have a capacitor rated 470F. This can be decoded as:
This means the capacitance of the capacitor is 47 x 10^0 = 47pF with 1% tolerance.
Is this all? No!! Some variations of capacitors are color coded, just like resistors. But this type of coding has become obsolete and more and more manufactures are shaking hands with numbering codes. If anyone of you is seriously enthusiastic, let me know and I will update this with capacitor color codes.