Appendix A

Resistor Color Codes

The resistor color coding system applies to carbon film, metal oxide film, fusible, precision metal film, and wirewound resistors of the axial lead type. This system is employed when the surface area is not sufficient to print the actual resistance value. Several color codes are used, the most common ones are the 4-band and 5-band codes. In the 4-band code, the first two bands represent the magnitude of the resistance, the third band is a multiplier for this value, and the fourth band encodes the error tolerance. In the 5-band code the first three bands represent the magnitude, the fourth band serves as a multiplier, and the fifth band is the error tolerance.

The color codes for the various bands are as follows:

To read the resistance value, first determine if it is a 4-band or a 5-band encoding. Then proceed to identify the tolerance band, which is usually either gold or silver. Starting at the opposite end, read the two or three magnitude bands and multiply this value by the multiplier band. For example, a resistor with four color bands, red, orange, brown, and gold, is a 230-Ohm resistor with a 5% error tolerance.

There are several online calculators that allow you to easily find the resistance value. You can locate these calculators by searching for the keywords: resistor color codes.