Resistor Color Code Calculator
Decode resistance values from color bands instantly
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Calculated Value
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What is a Resistor Color Code?
Resistor color codes are a standardized marking system used to identify the resistance value, tolerance, and sometimes the temperature coefficient of resistors. Since resistors are often too small to print numerical values on, manufacturers use colored bands to encode this information.
Each color represents a specific number (0-9), and the position of the band determines whether it represents a digit, multiplier, or tolerance. This system was developed in the 1920s and remains the industry standard for through-hole resistors today.
Understanding Band Types
4-Band Resistors
The most common type. Two bands for digits, one for multiplier, and one for tolerance (typically ±5% or ±10%).
5-Band Resistors
Precision resistors with three digit bands for better accuracy, one multiplier band, and one tolerance band (typically ±1% or ±2%).
6-Band Resistors
High-precision resistors that include an additional band for temperature coefficient, indicating how resistance changes with temperature.
Color Code Reference
| Color | Digit | Multiplier | Tolerance |
|---|---|---|---|
black | 0 | ×1 | - |
brown | 1 | ×10 | ±1% |
red | 2 | ×100 | ±2% |
orange | 3 | ×1000 | - |
yellow | 4 | ×10000 | - |
green | 5 | ×100000 | ±0.5% |
blue | 6 | ×1000000 | ±0.25% |
violet | 7 | ×10000000 | ±0.1% |
gray | 8 | ×100000000 | ±0.05% |
white | 9 | ×1000000000 | - |
gold | - | ×0.1 | ±5% |
silver | - | ×0.01 | ±10% |
none | - | - | ±20% |
Frequently Asked Questions
How do I read a resistor color code?
Start from the band closest to one end of the resistor. For a 4-band resistor, the first two bands are digits, the third is the multiplier, and the fourth (often separated) is tolerance. Hold the resistor so the tolerance band is on the right.
What does tolerance mean?
Tolerance indicates how much the actual resistance can vary from the stated value. For example, a 100Ω resistor with ±5% tolerance could actually measure anywhere from 95Ω to 105Ω. Gold (±5%) and silver (±10%) are common tolerance bands.
Which way do I read the resistor?
The tolerance band (usually gold or silver) is typically set apart from the other bands and should be on the right side. If there's no clearly separated band, look for a band that couldn't be a first digit (like gold or silver) and place that on the right.
Why use color codes instead of printing numbers?
Resistors are often very small, making printed numbers difficult to read. Color bands are visible from any angle, don't fade or wear off easily, and are standardized internationally. They also allow for quick identification without needing to read tiny text.