Calculator Tool

Enter the colors of your resistor to determine its resistance value and tolerance.

Understanding the Resistor Color Code

Resistors are fundamental passive electronic components that resist the flow of electric current. To make them easily identifiable, especially when they are small, manufacturers use a system of colored bands printed on their bodies. This system, known as the resistor color code, allows for quick and accurate determination of a resistor's nominal resistance value and its tolerance.

Most common resistors use a 4-band or 5-band color code. This calculator is designed for the standard 4-band system.

How the 4-Band Code Works:

• Band 1: First significant digit
  This band represents the first digit of the resistance value.
• Band 2: Second significant digit
  This band represents the second digit of the resistance value.
• Band 3: Multiplier
  This band indicates the power of 10 by which to multiply the first two digits to get the resistance value. For example, a Gold band means multiplying by 0.1, and a Red band means multiplying by 100.
• Band 4: Tolerance
  This band indicates the acceptable deviation from the nominal resistance value. A Gold band, for instance, means the actual resistance can be within +/- 5% of the stated value.

The Color-to-Value Mapping:

The standard mapping for resistors is as follows:

Digits: Black: 0, Brown: 1, Red: 2, Orange: 3, Yellow: 4, Green: 5, Blue: 6, Violet: 7, Gray: 8, White: 9

Multiplier: Black: x1 (10⁰), Brown: x10 (10¹), Red: x100 (10²), Orange: x1k (10³), Yellow: x10k (10⁴), Green: x100k (10⁵), Blue: x1M (10⁶), Violet: x10M (10⁷), Gold: x0.1 (10^-1), Silver: x0.01 (10^-2)

Tolerance: Brown: +/- 1%, Red: +/- 2%, Green: +/- 0.5%, Blue: +/- 0.25%, Violet: +/- 0.1%, Gray: +/- 0.05%, Gold: +/- 5%, Silver: +/- 10%, None: +/- 20%

Calculation Logic:

The nominal resistance is calculated by concatenating the values of the first two bands and then multiplying by the value of the third band (the multiplier).

Nominal Resistance = (Digit1 * 10 + Digit2) * Multiplier

The tolerance band specifies the acceptable range:

Actual Resistance Range = Nominal Resistance +/- (Nominal Resistance * Tolerance Percentage / 100)

Use Cases:

• Hobbyists and Students: Quickly identify unknown resistors for projects or learning electronics.
• Repair Technicians: Verify or replace faulty resistors in electronic circuits.
• Engineers: Double-check resistor values during circuit design and prototyping.