What do the colors on a resistor mean?

Most resistors have either 3 or 4 color bands. The fourth, if it is there, only indicates the tolerance, or how accurate the value is. For the first three bands, the following colors may be used: black = 0 or X1 brown = 1 or X10 red = 2 or X100 orange = 3 or X1000 yellow = 4 or X10000 green = 5 or X100000 blue = 6 or X1000000 violet = 7 gray = 8 white = 9 A resistor uses the first two color bands to form a 2 digit number, then a third band to add a multiplier. For instance, suppose you have a resistor that has a red, violet, brown color code. Decoding: red = 2 violet = 7 27 brown = X10 27 * 10 = 270 In this case, you are holding a 270 ohm resistor. How about a 2.2K resistor? Well, K = 1000, so 2.2K is the same as 2200 ohms. Reverse decoding: The first two bands would have to be red, red (22). To get to 2200 from 22 we have to multiply by 100, so the third band would also be red (X100). The last, or fourth band indicates how close to the nominal value the resistor is. The band colors are: none = 20% silver = 10% gold = 5% So, if the 2.2K resistor is red, red, red, silver, it means the actual resistance can be as much as 10% (or 220 ohms) higher or lower than 2.2K, or anywhere from 1980 ohms to 2420 ohms. You can get resistors with better accuracy than 5%, such as 2%, 1%, 0.1%. Some use three number bands and a fourth multiplier band, others have no bands at all, just the actual resistance printed as a number on the body. If in doubt, measure the resistor with an ohmmeter to be sure.