How to Read and Calculate 4-Band and 5-Band Resistor Values
Resistor colour codes are a standardized method for identifying the resistance value, tolerance, and sometimes other properties of resistors used in electrical and electronic circuits. Most resistors are too small to print their numerical values, so coloured bands make it easy to determine their properties quickly and accurately. This coding makes circuit assembly, troubleshooting, and replacement efficient for students, engineers, and professionals in electronics.
A typical resistor comes with 4, 5 or 6 coloured bands printed around its body. Each band represents a specific digit, a multiplier, or a tolerance value. The order and meaning of each band depend on the number of bands present. Understanding these codes allows you to read resistor values instantly, which is crucial for building and analyzing circuits.
To help with memorization, mnemonics like "Big Boys Race Our Young Girls But Violet Generally Wins" are commonly used, where each word’s first letter represents a resistor colour in order: Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Grey, White.
Resistor Colour Code Table
| Colour | Digit | Multiplier | Tolerance | Temperature Coefficient (ppm/°C) |
|---|---|---|---|---|
| Black | 0 | ×1 | – | – |
| Brown | 1 | ×10 | ±1% | 100 |
| Red | 2 | ×100 | ±2% | 50 |
| Orange | 3 | ×1,000 | ±3% | 15 |
| Yellow | 4 | ×10,000 | ±4% | 25 |
| Green | 5 | ×100,000 | ±0.5% | – |
| Blue | 6 | ×1,000,000 | ±0.25% | 10 |
| Violet | 7 | ×10,000,000 | ±0.10% | 5 |
| Grey | 8 | ×100,000,000 | ±0.05% | – |
| White | 9 | ×1,000,000,000 | – | – |
| Gold | – | ×0.1 | ±5% | – |
| Silver | – | ×0.01 | ±10% | – |
How to Read Resistor Colour Codes: Step-by-Step
- Identify the band closest to one edge as the starting band (read left to right).
- For a 4-band resistor:
- First band: First digit
- Second band: Second digit
- Third band: Multiplier (power of ten)
- Fourth band: Tolerance
- For a 5-band resistor:
- First three bands: Significant digits
- Fourth band: Multiplier
- Fifth band: Tolerance
- For a 6-band resistor:
- Bands one to three: Significant digits
- Fourth: Multiplier
- Fifth: Tolerance
- Sixth: Temperature coefficient
- Calculate resistance using the formula:
Worked Examples
Example 1: A 4-band resistor with colours: Brown, Black, Red, Gold.
First band (Brown) = 1
Second band (Black) = 0
Third band (Red, multiplier) = ×100
Fourth band (Gold) = ±5%
So, Resistance = (10) × 100 = 1000 Ω (1 kΩ) ±5%.
Example 2: A 5-band resistor with colours: Green, Blue, Black, Brown, Red.
Green = 5, Blue = 6, Black = 0 (first three digits = 560)
Brown (multiplier) = ×10, Red (tolerance) = ±2%
Resistance = 560 × 10 = 5600 Ω (5.6 kΩ) ±2%.
Key Tips and Common Exceptions
- If a resistor has a single black band, it is a zero-ohm link for PCB connections.
- Gold and silver bands sometimes appear as yellow and grey for special high-voltage applications.
- Some resistors may include a temperature coefficient band, mainly in 6-band types.
- Always start reading from the band nearest the resistor's edge.
- Mnemonic: Big Boys Race Our Young Girls But Violet Generally Wins (Black-Brown-Red-Orange-Yellow-Green-Blue-Violet-Grey-White).
Applications and Importance
Understanding resistor colour codes ensures accurate resistance selection in electronic assembly and analysis. Using incorrect resistance can alter circuit function or damage components. These codes save time and prevent mistakes, especially during troubleshooting or practical exams.
For more details on how resistors combine in a circuit, visit the page on Resistors in Series and Parallel Configuration.
Examine practical differences at Difference Between Resistance and Resistivity.
Quick Reference Table: Band Number and Meaning
| Number of Bands | 1st Band | 2nd Band | 3rd Band | 4th Band | 5th Band | 6th Band |
|---|---|---|---|---|---|---|
| 4 | Digit 1 | Digit 2 | Multiplier | Tolerance | – | – |
| 5 | Digit 1 | Digit 2 | Digit 3 | Multiplier | Tolerance | – |
| 6 | Digit 1 | Digit 2 | Digit 3 | Multiplier | Tolerance | Temp. Coefficient |
Practice and Further Learning
- Test your knowledge with resistor code practice on the Resistor Colour Codes main topic page.
- Explore how resistors combine at Resistors in Series and Parallel.
- Understand different resistor types at Types of Resistors.
- Review applications at Uses of Resistor for deeper insights.
By mastering resistor colour codes, you strengthen your understanding of electronics and improve your practical problem-solving in physics. Refer to the tables above whenever you need a quick check during study or experiments.
FAQs on Resistor Colour Codes Explained with Table & Examples
1. What is a resistor colour code?
Resistor colour code is a standardized system of coloured bands printed on resistors to indicate their resistance values and tolerance.
Key points:
- Each colour corresponds to a digit, multiplier, or tolerance percentage.
- Helps quickly identify resistor values in circuits without measuring tools.
2. How do you read a 4-band resistor colour code?
To read a 4-band resistor:
- Identify the bands from left to right (tolerance band is usually spaced further apart).
- The first two bands represent the first and second significant digits.
- The third band is the multiplier (number of zeros or multiplier factor).
- The fourth band gives the tolerance (how much the actual value may vary).
If the bands are Brown, Black, Orange, Gold—value is (10) × 1,000 = 10,000 Ω (10kΩ), tolerance ±5%.
3. How is a 5-band resistor colour code different from the 4-band code?
The 5-band resistor code includes:
- Three significant digits (first three bands).
- The fourth band as the multiplier.
- The fifth band as tolerance.
4. What are the standard resistor colour codes and their values?
The standard resistor colour codes are:
- Black - 0
- Brown - 1
- Red - 2
- Orange - 3
- Yellow - 4
- Green - 5
- Blue - 6
- Violet - 7
- Grey - 8
- White - 9
- Gold - multiplier ×0.1, tolerance ±5%
- Silver - multiplier ×0.01, tolerance ±10%
5. How do you calculate resistor value using colour bands?
To calculate resistor value from colour bands:
- Write the value of each colour according to the standard table (first 2/3 bands for digits; next band for multiplier; final band for tolerance).
- Form the number with the digits, multiply by the multiplier.
- Add or subtract the tolerance for minimum and maximum values.
6. What is the tolerance band in resistor colour codes?
The tolerance band shows the permissible variation in the resistor's value from its nominal value.
Common colours:
- Brown: ±1%
- Red: ±2%
- Green: ±0.5%
- Blue: ±0.25%
- Violet: ±0.1%
- Grey: ±0.05%
- Gold: ±5%
- Silver: ±10%
- No band: ±20%
7. What are the colour codes for 1K and 10K resistors?
1kΩ (1,000 ohms):
- 4-band: Brown, Black, Red, Gold (±5%)
- 4-band: Brown, Black, Orange, Gold (±5%)
8. How do you memorise the resistor colour code sequence easily?
Mnemonics help memorise the sequence:
- BB ROY Great Britain Very Good Wife (Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Grey, White)
- Or "Big Boys Race Our Young Girls But Violet Goes Willingly."
9. Why are colour codes used for resistors?
Colour codes offer a fast, standard, and reliable way to identify resistor values, tolerances, and properties without measurement instruments.
- Beneficial in electronics manufacturing
- Reduces space compared to printed numbers
- Essential for error-free circuit design and repair
10. What are common mistakes students make while reading resistor colour codes?
Common mistakes:
- Reading bands from the wrong side (tolerance band should be last).
- Confusing similar colours (e.g., red vs. brown, orange vs. gold).
- Using the wrong order of digits and multipliers.
- Not considering tolerance, leading to miscalculations in numericals.
11. What is the difference between 4-band, 5-band, and 6-band resistors?
Difference:
- 4-band: 2 significant digits, 1 multiplier, 1 tolerance band.
- 5-band: 3 significant digits, 1 multiplier, 1 tolerance band (higher precision).
- 6-band: Same as 5-band, plus 1 temperature coefficient band for stability in changing temperatures.
12. Where can I practice resistor colour code questions or use a colour code calculator?
You can practice resistor colour code questions and access an online resistor colour code calculator on trusted educational and exam preparation platforms, including dedicated practice problems, quizzes, and interactive calculators offered on the page. These resources help you check answers instantly and master the topic for exams.
