Resistor Color Code Calculator

Welcome to the Resistor Color Code Calculator, a comprehensive tool for electronics hobbyists, students, and professionals. This interactive calculator helps you decode resistor color bands and determine resistance values instantly. Whether you are working with standard 4-band resistors or precision 5-band and 6-band components, this tool provides accurate results with visual feedback.

What is a Resistor Color Code?

Resistors use colored bands to indicate their resistance value, tolerance, and sometimes temperature coefficient. This color-coding system was developed because resistors are often too small for printed numbers to be readable. The system is standardized internationally, making it universal across manufacturers.

Each color represents a specific digit (0-9), multiplier value, or tolerance percentage. By reading the bands in sequence, you can determine the exact resistance value of any resistor.

Types of Resistor Band Systems

4-Band Resistors (Standard)

The most common type found in general electronics:

• Band 1: First significant digit (0-9)
• Band 2: Second significant digit (0-9)
• Band 3: Multiplier (number of zeros)
• Band 4: Tolerance (gold = ±5%, silver = ±10%)

5-Band Resistors (Precision)

Used when higher precision is required:

• Band 1: First significant digit
• Band 2: Second significant digit
• Band 3: Third significant digit
• Band 4: Multiplier
• Band 5: Tolerance

6-Band Resistors (High Precision)

Include temperature coefficient for critical applications:

• Bands 1-5: Same as 5-band resistors
• Band 6: Temperature coefficient (ppm/°C)

Color Code Reference Chart

How to Read Resistor Color Bands

Step 1: Orient the Resistor

Hold the resistor with the tolerance band (gold, silver, or wider spacing) on the right side. The tolerance band is typically slightly separated from the other bands or positioned closer to one end.

Step 2: Read the Significant Figures

Read the first two bands (4-band) or first three bands (5/6-band) from left to right. Each color represents a digit from 0 to 9.

Step 3: Apply the Multiplier

The multiplier band tells you what to multiply the base number by. This is essentially the number of zeros to add for standard values.

Step 4: Note the Tolerance

The tolerance indicates how much the actual resistance may vary from the nominal value. Gold (±5%) is more precise than silver (±10%).

Common Resistor Values and Examples

Example 1: Brown-Black-Red-Gold (4-band)

• Brown (1) + Black (0) = 10
• Red multiplier = ×100
• Result: 10 × 100 = 1,000Ω (1kΩ) ±5%

Example 2: Yellow-Violet-Orange-Gold (4-band)

• Yellow (4) + Violet (7) = 47
• Orange multiplier = ×1,000
• Result: 47 × 1,000 = 47,000Ω (47kΩ) ±5%

Example 3: Brown-Black-Black-Brown-Brown (5-band)

• Brown (1) + Black (0) + Black (0) = 100
• Brown multiplier = ×10
• Brown tolerance = ±1%
• Result: 100 × 10 = 1,000Ω (1kΩ) ±1%

Understanding Tolerance

Tolerance indicates the precision of a resistor. A 1kΩ resistor with ±5% tolerance will actually measure between 950Ω and 1,050Ω. For most hobby projects, ±5% (gold) tolerance is sufficient. Precision circuits may require ±1% (brown) or better.

Tolerance Comparison

• ±20% (no band): Rarely used today, very imprecise
• ±10% (silver): General purpose, economy grade
• ±5% (gold): Standard for most applications
• ±1% (brown): Precision applications
• ±0.1% or better: Measurement and instrumentation

Temperature Coefficient (6-Band Resistors)

The temperature coefficient indicates how much resistance changes with temperature, measured in parts per million per degree Celsius (ppm/°C). Lower values mean more stable resistance across temperature changes:

• Brown (100 ppm/°C): Standard stability
• Red (50 ppm/°C): Better stability
• Orange (15 ppm/°C): High stability
• Blue (10 ppm/°C): Very high stability

Tips for Identifying Resistors

• Good lighting: Use bright, natural light to distinguish colors accurately
• Watch for brown vs. red: These can look similar; brown is darker
• Blue vs. violet: Blue is brighter; violet has a purple tint
• Gray vs. silver: Silver has a metallic sheen; gray is matte
• Use a magnifier: Small resistors benefit from magnification
• Verify with multimeter: When in doubt, measure the actual resistance

Frequently Asked Questions

How do I read a 4-band resistor?

For a 4-band resistor: The first band represents the first digit (0-9), the second band represents the second digit (0-9), the third band is the multiplier (number of zeros to add), and the fourth band indicates the tolerance percentage. For example, Brown-Black-Red-Gold means 1-0 × 100 = 1000Ω (1kΩ) with ±5% tolerance.

What is the difference between 4-band and 5-band resistors?

4-band resistors have two significant figures, while 5-band resistors have three significant figures for greater precision. 5-band resistors are used when more accurate resistance values are needed, such as in precision circuits. The extra band provides one more digit before the multiplier.

What does the 6th band on a resistor indicate?

The 6th band on a resistor indicates the temperature coefficient in parts per million per degree Celsius (ppm/°C). This tells you how much the resistance will change with temperature. Brown = 100 ppm/°C, Red = 50 ppm/°C, Orange = 15 ppm/°C, etc. Lower values mean more stable resistance across temperature changes.

What do gold and silver bands mean on a resistor?

Gold and silver bands have two uses: As a multiplier, gold means ×0.1 and silver means ×0.01 (for resistors under 10Ω). As a tolerance band, gold means ±5% tolerance and silver means ±10% tolerance. Gold tolerance is more precise than silver.

How do I identify which end of the resistor to start reading from?

Start reading from the end with the tolerance band furthest away. The tolerance band (gold, silver, or no band) is usually separated by a slightly larger gap from the other bands. Additionally, the first band is often closer to one end of the resistor body. If there is no tolerance band, assume ±20% tolerance.

Additional Resources

• Electronic Color Code - Wikipedia
• Resistor - Wikipedia
• Resistor Color Codes Tutorial - Electronics Tutorials