Resistor Color Codes
|Color||1st Digit (A)||2nd Digit (B)||Multiplier (C)||Tolerance (D)|
Resistors are read starting from the line closest to the end of the resistor. They will either have 4 bands or 5 bands. If there are four bands then the first two are the value, the third is the multiplier, and the fourth is the precision. If there are five bands then the first three are the value, the fourth is the multiplier, and the fifth is the precision.
For example take the following resistor which has bands Green, Blue, Yellow, and Gold. Since there are four bands the third band is the multiplier and the fourth band is the tolerance. Looking at the chart below:
Green = 5 (tens place)
Blue = 6 (ones place)
Yellow = 10KΩ
Gold = 5%
Understanding the value. Put the 5 and 6 together for 56 then multiply by 10KΩ - 56*10KΩ=560kΩ.
Understanding the tolerance. The tolerance is +/-5% - 560kΩ*5%=28kΩ which means the resistor may be 28kΩ lower or higher than the stated value. 560kΩ-28kΩ=532kΩ. 560kΩ+28kΩ=588kΩ. So the acceptable resistance of this resistor is between 532KΩ and 588KΩ.
Above is an example of a 5 band resistor. They are usually higher precision resistors. In this case the band colors are red, orange, violet, black, and brown.
Red = 2 (hundreds place)
Orange = 3 (tens place)
Violet = 7 (ones place)
Black = 1Ω
Brown = 1%
Mnemonics for remembering color codes. Mnemonics are the only way I can remember the color codes but times have changed in the 20+ years since my instructor told me the mnemonic for remembering resistor color codes and it would be too offensive for this site today. However when I began researching modern mnemonics used to remember resistor color codes in schools I didn't find any of them nearly as effective. So here is a good list of various mnemonics for remembering resistor color codes from Wikipedia.