Gnome resistor color code calculator To allow for identification, resistors are usually marked with colored bands. Often refereed to as color codes, these markings are indicative of their resistance, tolerance and temperature coefficient. gResistror is a great program that will help you translate a resistor color codes into a readable value. All you have to do is watch the colors on the resistor and then enter them in the program. As you enter you'll see that the resistor value is changing according to the selected color.