Resistor Color Code Calculator

Decode Resistors Instantly

This interactive calculator helps you decode the color bands on a standard 4-band resistor to determine its resistance value and tolerance. Select the colors for each band to instantly see its value in Ohms (Ω).

The Color Code System Explained

For a 4-band resistor:

• 1st Band: The first significant digit of the resistance value.
• 2nd Band: The second significant digit.
• 3rd Band (Multiplier): A power-of-10 multiplier. The number of zeros to add after the first two digits.
• 4th Band (Tolerance): Indicates the acceptable percentage of error in the resistor's value (e.g., Gold is ±5%).

How to Use the Calculator

1. Hold the resistor with the tolerance band (usually gold or silver) on the right.
2. Read the colors from left to right.
3. Select the corresponding colors for Band 1, Band 2, the Multiplier, and the Tolerance in the calculator.
4. The resistance value will be displayed automatically.

Real-World Example

A resistor has the following bands: Brown, Black, Red, Gold.

• Band 1 (Brown): 1

• Band 2 (Black): 0

• Multiplier (Red): ×100 (or add 2 zeros)

• Tolerance (Gold): ±5%

• Value: The first two digits are 10. The multiplier is 100. So, 10 × 100 = 1,000 Ω, or 1 kΩ.

• Final Reading: 1 kΩ with a ±5% tolerance.

Frequently Asked Questions (FAQ)

• What about 5-band resistors? 5-band resistors are used for higher precision. The first three bands are significant digits, the fourth is the multiplier, and the fifth is the tolerance. This calculator is currently optimized for the more common 4-band resistors.
• What if there is no tolerance band? If the fourth band is missing, the tolerance is assumed to be ±20%.
• How do I remember the color code? A popular mnemonic is: "Big Boys Race Our Young Girls, But Violet Generally Wins." (Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Grey, White for digits 0-9).