Resistor Color Code Calculator
Select the color bands to decode the resistor value instantly.
Input
Result
How It Works
For a 4-band resistor: Band 1 is the first digit, Band 2 is the second digit, Band 3 is the multiplier, Band 4 is the tolerance.
For a 5-band resistor: Band 1-3 are the first three digits, Band 4 is the multiplier, Band 5 is the tolerance.
Understanding Resistor Color Codes
Resistor color codes are a standardized marking system defined by IEC 60062 that uses colored bands to indicate a resistor's resistance value, tolerance, and sometimes temperature coefficient. This system allows engineers and technicians to quickly identify resistor values without needing measurement tools.
How to Read Resistor Color Codes
For a 4-band resistor, the first two bands represent significant digits, the third band is the multiplier, and the fourth band indicates tolerance. The formula is:
For example, a resistor with Brown-Black-Orange-Gold bands reads as: (1×10 + 0) × 1,000 = 10 kΩ ±5%.
For a 5-band resistor, the first three bands are significant digits, the fourth is the multiplier, and the fifth is tolerance. This provides higher precision for tight-tolerance components.
Engineering Applications
- Circuit prototyping: Quickly identify the correct resistor values during breadboard assembly without reaching for a multimeter.
- PCB inspection: Verify component values during quality control and board rework processes.
- Component sorting: Organize loose resistor inventory by reading color codes instead of testing each one.
- LED current limiting: Select the right resistor to limit current through LEDs based on supply voltage and desired brightness.
- Voltage dividers: Choose appropriate resistor pairs to achieve target output voltages in sensor circuits.
Frequently Asked Questions
What happens if I read the resistor from the wrong end?
Reading from the wrong end will typically give you an invalid resistance value. Most resistors have the tolerance band slightly separated from the other bands — always start reading from the end opposite the tolerance band. Some resistors also have a wider gap before the tolerance band as a visual cue.
What is the difference between 4-band and 5-band resistors?
A 4-band resistor uses two significant digits, providing values like 10 kΩ or 47 kΩ. A 5-band resistor uses three significant digits, enabling more precise values like 10.5 kΩ or 47.5 kΩ. Five-band resistors are typically used in precision applications where tighter tolerance (1% or better) is required.
Can I use this calculator for surface-mount (SMD) resistors?
No — SMD resistors use a numerical code system (e.g., "103" = 10 kΩ) rather than color bands. This calculator is designed for through-hole resistors with color-coded bands. We may add an SMD code calculator in the future.
What does the temperature coefficient band (6th band) mean?
On 6-band resistors, the sixth band indicates the temperature coefficient in ppm/°C (parts per million per degree Celsius). For example, a brown band means 100 ppm/°C, meaning the resistance changes by 0.01% for each degree of temperature change. This is important in precision and high-temperature applications.
Why do some resistors have a gold or silver body?
A gold or silver body color on older resistors typically indicates a wirewound construction. However, body color is not part of the IEC 60062 color code standard and should not be confused with the band markings. Always rely on the painted bands, not the body color.