Resistor Color Code Calculator
Decode resistor values from color bands with 100% accuracy. Calculate resistance, tolerance, and temperature coefficient for 4, 5, and 6 band resistors.
4-Band Resistor
Standard precision resistor with ±5% tolerance
Enter Resistance Value
Understanding Resistor Color Codes
Resistor color codes are a standardized system used to identify the resistance value, tolerance, and sometimes temperature coefficient of resistors. This system was developed to provide a compact way to mark resistor values on small components where numerical printing would be difficult to read.
How Resistor Color Codes Work
The color code system uses colored bands painted around the resistor body to represent different digits and multipliers. The position and number of bands determine how to read the resistor value:
4-Band Resistors (Standard)
Band 1: First significant digit
Band 2: Second significant digit
Band 3: Multiplier (number of zeros)
Band 4: Tolerance (accuracy)
5-Band Resistors (Precision)
Band 1: First significant digit
Band 2: Second significant digit
Band 3: Third significant digit
Band 4: Multiplier (number of zeros)
Band 5: Tolerance (accuracy)
6-Band Resistors (High Precision)
Band 1-3: Same as 5-band resistor
Band 4: Multiplier
Band 5: Tolerance
Band 6: Temperature coefficient (ppm/°C)
Color Code Reference Table
| Color | Digit | Multiplier | Tolerance | Temp Coeff |
|---|---|---|---|---|
| Black | 0 | ×1 | - | - |
| Brown | 1 | ×10 | ±1% | 100 ppm/°C |
| Red | 2 | ×100 | ±2% | 50 ppm/°C |
| Orange | 3 | ×1K | - | 15 ppm/°C |
| Yellow | 4 | ×10K | - | 25 ppm/°C |
| Green | 5 | ×100K | ±0.5% | - |
| Blue | 6 | ×1M | ±0.25% | 10 ppm/°C |
| Violet | 7 | ×10M | ±0.1% | 5 ppm/°C |
| Grey | 8 | ×100M | ±0.05% | - |
| White | 9 | ×1G | - | 1 ppm/°C |
| Gold | - | ×0.1 | ±5% | - |
| Silver | - | ×0.01 | ±10% | - |
Reading Direction and Orientation
Resistors should be read from left to right, starting with the band closest to one end. The tolerance band (usually gold or silver) is typically positioned closer to one end, helping you identify the correct reading direction. If you're unsure, try both directions and see which gives a standard resistor value.
Common Resistor Values and Applications
Resistors are manufactured in standard values following the E-series (E12, E24, E96, E192). Common applications include:
- Pull-up/Pull-down resistors: 1kΩ - 10kΩ
- Current limiting: 220Ω - 1kΩ for LEDs
- Voltage dividers: Various values depending on ratio needed
- Timing circuits: 1kΩ - 1MΩ with capacitors
- Biasing circuits: 10kΩ - 100kΩ in amplifiers
Tolerance and Precision
Tolerance indicates how much the actual resistance can vary from the nominal value. Lower tolerance means higher precision:
- ±20% (No band): Very old resistors
- ±10% (Silver): Standard tolerance
- ±5% (Gold): Common precision
- ±1% (Brown): High precision
- ±0.5% (Green): Very high precision
- ±0.25% (Blue): Ultra precision
- ±0.1% (Violet): Laboratory grade
Temperature Coefficient
The temperature coefficient (6th band) indicates how much the resistance changes with temperature, measured in parts per million per degree Celsius (ppm/°C). Lower values indicate better temperature stability, crucial for precision applications.
Tips for Accurate Reading
- Use good lighting and magnification if needed
- Clean the resistor surface if dirty or oxidized
- Be aware that some colors can appear similar (red vs. orange, brown vs. red)
- Use a multimeter to verify your reading
- Consider the context - check if the calculated value makes sense in the circuit
Modern Alternatives
While color codes remain standard for through-hole resistors, surface-mount resistors use numerical codes. Some modern resistors also include QR codes or direct numerical printing for easier identification.