Resistor Color Code Decoder
Quickly decode resistor color bands and find the resistance value, tolerance, and temperature coefficient with this free online tool. Support for 3, 4, 5, and 6 band resistors.
Resistor Color Code Decoder
Resistor Bands Input
Select the number of bands and colors to decode your resistor's value.
Brown (1)
Black (0)
Red (2)
Gold
Resistor Value
Enter band colors and click Calculate to see results.
Resistor Color Code Information
What is Resistor Color Coding?
Resistor color coding is a standardized method used to indicate the resistance value, tolerance, and temperature coefficient of resistors. Since most resistors are small in size, it's impractical to print numbers directly on them.
Instead, colored bands are used to represent different values. These color codes are standardized according to IEC 60062:2016, making it easy for engineers and hobbyists to identify resistor values worldwide.
Ohm's Law
$$R = \frac{V}{I}$$
Where R is resistance in ohms (Ω), V is voltage in volts (V), and I is current in amperes (A).
Each colored band on a resistor represents a specific value. The colors are read from left to right, with the first bands representing significant digits, followed by a multiplier, and then tolerance and temperature coefficient bands (if present).
How to Use This Resistor Color Code Decoder
This tool helps you decode the colored bands on a resistor to determine its value, tolerance, and temperature coefficient.
To decode a resistor's color bands:
- Select the number of bands on your resistor (3, 4, 5, or 6).
- Click on the colors that match each band on your resistor, in order from left to right.
- The tool will automatically calculate the resistance value, tolerance range, and temperature coefficient (if applicable).
- The results will show the nominal resistance value along with the minimum and maximum values based on the tolerance.
Tips for Reading Resistor Color Codes
- Most resistors have a gap or wider spacing before the tolerance band to help identify the reading direction.
- If there's a gold or silver band, it's usually the tolerance band and will be on the right side of the resistor.
- For more accurate measurements, especially with high-precision resistors, consider using a multimeter.
Understanding Resistor Color Codes
Resistors use a standardized color coding system to indicate their resistance value, tolerance, and temperature coefficient. The number of bands on a resistor determines how the colors are interpreted.
Number of Bands
- 3-band resistors: Two significant digits + multiplier. Default tolerance is ±20%.
- 4-band resistors: Two significant digits + multiplier + tolerance. Most common type.
- 5-band resistors: Three significant digits + multiplier + tolerance. Used for higher precision.
- 6-band resistors: Three significant digits + multiplier + tolerance + temperature coefficient. Used for high-precision applications.
Color Code Values
Each color represents specific values depending on its position on the resistor:
| Color | Digit Value | Multiplier | Tolerance |
|---|---|---|---|
Black (0) | 0 | ×1 | - |
Brown (1) | 1 | ×10 | ±1% |
Red (2) | 2 | ×100 | ±2% |
Orange (3) | 3 | ×1,000 | ±3% |
Yellow (4) | 4 | ×10,000 | ±4% |
Green (5) | 5 | ×100,000 | ±0.5% |
Blue (6) | 6 | ×1,000,000 | ±0.25% |
Violet (7) | 7 | ×10,000,000 | ±0.1% |
Grey (8) | 8 | ×100,000,000 | ±0.05% |
White (9) | 9 | ×1,000,000,000 | - |
Gold | - | ×0.1 | ±5% |
Silver | - | ×0.01 | ±10% |
None | - | - | ±20% |
A common mnemonic to remember the color sequence is: 'BB ROY G. BIV GW' (Black, Brown, Red, Orange, Yellow, Green, Blue, Indigo (Violet), Grey, White).
Applications and Examples
Resistors are fundamental components in electronic circuits with numerous applications across various devices and systems.
Common Applications of Resistors
- Current limiting: Protecting LEDs and other components from excessive current.
- Voltage division: Creating specific voltage levels from a higher voltage source.
- Biasing: Setting operating points in transistor amplifiers.
- Pull-up/pull-down: Defining logic states in digital circuits when inputs are floating.
Standard Resistor Values
Resistors are manufactured in standardized series like E12 (12 values per decade) and E24 (24 values per decade). These standard values make it easier for designers to select appropriate resistors for their circuits.
E12 Series (12 values per decade):
10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82
E24 Series (24 values per decade):
10, 11, 12, 13, 15, 16, 18, 20, 22, 24, 27, 30, 33, 36, 39, 43, 47, 51, 56, 62, 68, 75, 82, 91
Frequently Asked Questions
How do I know which direction to read the resistor bands?
The tolerance band (usually gold or silver) is typically placed on the right side of the resistor. If there's no gold or silver band, look for a gap or wider spacing between bands - this gap usually precedes the tolerance band. If still uncertain, test with a multimeter.
What if I'm colorblind or have difficulty distinguishing certain colors?
Consider using a multimeter to measure the resistance directly. Alternatively, there are smartphone apps that can identify resistor colors using the camera. You can also ask someone else to help identify the colors, or use this calculator with someone's assistance.
Why are there different numbers of bands on resistors?
Different band counts provide varying levels of precision and information. 3-band resistors offer basic values, 4-band adds tolerance information, 5-band provides more precise values, and 6-band adds temperature coefficient information for high-precision applications.
What does the temperature coefficient band mean?
The temperature coefficient band (found on 6-band resistors) indicates how much the resistance value changes with temperature. It's measured in parts per million per degree Celsius (ppm/°C). Lower values mean more stable resistance across temperature changes.
Are SMD (surface mount) resistors coded the same way?
No, SMD resistors typically use a numerical code instead of color bands. They usually have a 3 or 4 digit code where the first two or three digits are significant figures and the last digit is the multiplier (number of zeros to add).