Resistor Calculator is very useful program that allows you to calculate the value of resistors, generate the color code, and calculate resistors for LED circuits. Resistors are electronic components that are present in all the electronic circuits. They determine the electric current that must flow in an electric circuit for a given voltage. Resistors are marked with colored bands which indicate their value and tolerance. The resistance value is measured in ohms (Ω). The tolerance indicates the percentage of accuracy of the resistance value. With Resistor Calculator you can calculate the resistor value by selecting the colors of each band, or you can introduce the resistor value to generate its color code. If you want to generate the color code of a resistor you have to type the resistance value and the percentage of tolerance (it is better to select the temperature coefficient if it is known). After you have introduced these values you can select between two series, where each one contains different compatible resistors. Some resistors vary in number of bands and significant digits. To calculate resistors for LED circuits, you have the option to calculate resistors for single LED, and LED circuits in series or parallel connection. You only have to introduce the supply voltage, voltage drop across the LED, and the current of LED (for LEDs in series or parallel connection you have o introduce the count of LEDs in the circuit). After introducing these parameters you can obtain the resistor value, the power dissipation, and the resistor color code.