How to Read Resistor Color Codes
- 1). Count the number of bands on the resistor. There will be four, five or six bands. Four-band resistors have two significant digits, and five- and six-band resistors have three significant digits. A link to a color-code chart is provided in the Resources section.
- 2). Consult the resistor color code chart, and write down the significant digits. The bands grouped together at one end of the resistor are the significant digits. For example, if the first three bands of a five-band resistor are red, blue and yellow, the significant digits are 2, 6 and 4. Write down 264.
- 3). Compare the color-code chart to the next band for the position of the decimal point. The number refers to the number of zeros to the right of the significant digits except for gold or silver. Gold moves the decimal point one place to the left, and silver moves it two places to the left. If, for example, the significant digits are 264, and the next band is black, which stands for zero, the resistance is 264 ohms because there are no zeros after the significant digits. If, for example, the band were red, which stands for 2, instead of black, the resistance would be 26,400 ohms.
- 4). Compare the color-code chart to the next band for the resistor's tolerance. The tolerance is a plus or minus percentage. Unlike the significant digits and multiplier bands, the tolerance bands have different numbers. For example, a 26,400 ohm resistor with a silver tolerance band, which stand for plus or minus 10 percent, will have a value ranging from 23,760 ohms (26,400 - 10 percent) to 29,040 ohms (26,400 + 10 percent).
- 5). Consult the resistor color-code chart for the temperature coefficient on six-band resistors. The color code of the sixth band gives the temperature coefficient directly.
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