Resistors are small parts used in almost every electronic circuit, and their values are shown with a color code instead of printed numbers. These colored bands represent resistance, tolerance, and sometimes temperature effects. The system is standard worldwide, making it reliable and easy to use. This article explains the resistor color code in detail.
Resistor Color Code Basics
The resistor color code is a simple system that uses colored bands to show basic details about a resistor. These colors stand for the resistance value, multiplier, tolerance, and sometimes the temperature coefficient. Instead of printing numbers, the bands make it easy to fit this information onto very small parts.
This method is standardized under IEC 60062, so the meaning of the colors is the same everywhere. It is used on axial resistors, which are too small to print readable numbers on. By reading the colors in the right order, you can figure out the resistor’s value quickly.
It is also basic to know that the physical size of the resistor does not tell you its resistance. The size is connected to its wattage rating, which shows how much power it can handle before overheating. Larger resistors handle more power, while smaller ones handle less.
Reading Resistor Color Codes Correctly
Reading a resistor starts with knowing which side to begin from. The tolerance band, almost always gold or silver, is placed at the far right. This makes it easier to tell where the sequence of value bands begins. Many resistors also include a slightly wider space before the tolerance band, helping separate it from the other bands.
A simple guideline is that the first color band is closest to one of the resistor’s leads. Starting from the wrong side can give you the wrong value, so checking the orientation is required.
In some cases, such as with older or heat-damaged resistors, the colors may be hard to read or faded. When this happens, it’s best not to rely on the bands alone. Use a digital multimeter to confirm the actual resistance. This avoids mistakes and ensures the resistor still matches its expected rating.
4-Band Resistor Code Basics
The 4-band color code is the most common system for resistors, especially in everyday electronics. It uses four color bands, each representing a different part of the value:
• Band 1: First digit of the resistance value
• Band 2: Second digit of the resistance value
• Band 3: Multiplier (power of ten)
• Band 4: Tolerance (accuracy range)
If a resistor has no tolerance band at all, it should be read as having a ±20% tolerance.
Example of 4-Band Reading
A resistor marked Yellow – Violet – Red – Gold would be read as:
• Yellow = 4
• Violet = 7
• Red = ×100
• Gold = ±5% tolerance
This equals 4,700 Ω (4.7 kΩ) ±5%. The 4-band system is simple and effective, which is why it’s used in most general-purpose resistors found in consumer electronics.
5-Band Resistor Color Code
The 5-band color code is used when resistors need greater accuracy than the standard 4-band system. These resistors add an extra digit to improve precision, making them common in sensitive analog circuits, measurement equipment, and precision devices.
The five bands represent:
• Band 1: First digit
• Band 2: Second digit
• Band 3: Third digit
• Band 4: Multiplier
• Band 5: Tolerance
This system allows for more exact resistance values that can’t be expressed with only two digits.
Example of 5-Band Reading
Take the resistor marked Brown – Yellow – Violet – Black – Green:
• Brown = 1
• Yellow = 4
• Violet = 7
• Black = ×1
• Green = ±0.5% tolerance
Final value = 147 Ω ±0.5%. The tighter tolerance ensures the resistor performs very close to its stated value, which is important when small variations could affect circuit performance.
6-Band Resistor Color Code
The 6-band color code builds on the 5-band system by adding one more piece of information: the temperature coefficient (tempco). This extra band shows how much the resistance value will change with temperature. It is measured in parts per million per degree Celsius (ppm/°C).
The six bands represent:
• Band 1: First digit
• Band 2: Second digit
• Band 3: Third digit
• Band 4: Multiplier
• Band 5: Tolerance
• Band 6: Temperature coefficient
This code is used when circuits need both high precision and predictable behavior under changing temperatures. It is common in industrial controls, aerospace systems, and precision test instruments.
Example of 6-Band Reading
For a resistor marked Orange – Red – Brown – Brown – Green – Red:
• Orange = 3
• Red = 2
• Brown = 1
• Brown = ×10
• Green = ±1% tolerance
• Red = 50 ppm/°C
Final value = 3.21 kΩ ±1% with a tempco of 50 ppm/°C. This means the resistor is accurate and stable, even when exposed to temperature changes, which is basic for high-reliability designs.
Standard Resistor Color Coding and Values
| Color Bands (Left to Right) | Value Calculation (Digits × Multiplier) | Resistance Value | Tolerance |
|---|---|---|---|
| 1. Yellow – Violet – Orange – Gold | 47 × 10³ | 47 kΩ | ± 5% |
| 2. Green – Red – Gold – Silver | 5.2 × 1 | 5.2 Ω | ± 10% |
| 3. White – Violet – Black (blank tol.) | 97 × 1 | 97 Ω | ± 20% |
| 4. Orange – Orange – Black – Brown – Violet | 330 × 10 | 3.3 kΩ | ± 0.1% |
| 5. Brown – Green – Grey – Silver – Red | 158 × 0.01 | 1.58 Ω | ± 2% |
| 6. Blue – Brown – Green – Silver – Blue | 615 × 0.01 | 6.15 Ω | ± 0.25% |
Resistor Value Series and Their Tolerances
To simplify mass manufacturing, the IEC (International Electrotechnical Commission) introduced standard resistor values in 1952, later published as IEC 60063:1963. Known as the preferred values or E-series, these standards are also applied to capacitors, Zener diodes, and inductors. By spacing values evenly on a logarithmic scale, manufacturers ensure compatibility, easier stocking, and consistent designs across different suppliers.
| E Series | Tolerance | Values per Decade | Typical Values (Examples |
|---|---|---|---|
| E3 | ±36% (≈40–50%) | 3 | 1.0, 2.2, 4. |
| E6 | ±20% | 6 | 1.0, 1.5, 2.2, 3.3, 4.7, 6.8 |
| E12 | ±10% | 12 | 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2 |
| E24 | ±5% | 24 | 1.0, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4 … 9.1 |
| E48 | ±2% | 48 | 1.00, 1.05, 1.10, 1.15, 1.21 … up to 9.53 |
| E96 | ±1% | 96 | 1.00, 1.02, 1.05, 1.07 … up to 9.76 |
| E192 | ±0.5%, ±0.25%, tighter | 192 | Very fine increments, used in precision resistors |
Conclusion
The resistor color code is a clear way to show important details on components that are too small for numbers. By reading the bands in the right order, resistance values, tolerances, and even temperature behavior can be found. Knowing this system helps ensure accuracy and dependable results in electronic circuits.
Frequently Asked Questions
Q1. Why do some resistors have numbers instead of color bands?
Because larger and SMD resistors have enough space to print numerical codes instead of using bands.
Q2. Are resistor color codes used on all resistors?
No, they are mainly on axial resistors. SMD and wirewound resistors use printed codes or datasheets.
Q3. Does orientation matter when reading resistor bands?
Yes, for reading only. The resistor works either way, but the bands must be read from the correct side.
Q4. Can resistor colors fade without overheating?
Yes, sunlight, moisture, or chemicals can cause fading even without heat damage.
Q5. Are resistor color codes the same worldwide?
Yes, the IEC 60062 standard makes them consistent globally.
Q6. Are color codes as accurate as measuring with a multimeter?
No, they show the nominal value only. A multimeter gives the exact resistance.