Resistor color coding : Explain

BY ADMIN January 22, 2025

What is a Resistor?

A resistor is an electronic component that resists the flow of electricity. It is used in circuits to limit the amount of current that flows through a part of the circuit. Each resistor has a value, which tells us how much resistance it offers to the current.

What is Resistor Color Coding?

Resistor values are often marked using colored bands on the body of the resistor. These colored bands tell us the resistance value of the resistor and sometimes its tolerance (how accurate the value is).

A typical resistor has 4 color bands, but some resistors may have 5 or 6 bands, depending on how precise they are. But for now, let’s focus on 4-band resistors, which are the most common.

How Do We Read the Color Bands?

Each color corresponds to a number, and these numbers are used to determine the resistance value of the resistor. Here’s a chart showing the number each color represents:

Color Number
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Gray 8
White 9

The 4 Bands on a Resistor

A 4-band resistor has four color bands, each with a specific purpose:

  1. First Band: The first band represents the first digit of the resistor value.
  2. Second Band: The second band represents the second digit of the resistor value.
  3. Third Band: The third band tells us the multiplier (how much to multiply the first two digits by).
  4. Fourth Band: This is the tolerance, which tells us how much the actual value could differ from the stated value.

Example: Let’s break it down with an example resistor:

Say the color bands on the resistor are:

  • Red (first band)
  • Green (second band)
  • Brown (third band)
  • Gold (fourth band)

Now, let’s decode this step-by-step:

  1. First Band – Red: Red corresponds to the number 2.
  2. Second Band – Green: Green corresponds to the number 5.
  3. Third Band – Brown: Brown is the multiplier. It means multiply the first two digits by 10 (10^1 = 10).
  4. Fourth Band – Gold: Gold indicates the tolerance, which is ±5%. This means the actual value of the resistor can be 5% higher or lower than the printed value.

Calculation of the Value:

  • The first two digits are 2 and 5, so we get 25.
  • The multiplier is 10, so we multiply 25 by 10.
  • 25 × 10 = 250 ohms.

So, this resistor has a value of 250 ohms with a tolerance of ±5%.

What Does Tolerance Mean?

  • The tolerance (the fourth band) tells you how much the resistor’s actual value can vary from the marked value. For example:
    • Gold means ±5% (so the resistor value can be 5% higher or lower).
    • Silver means ±10%.
    • No band (some resistors) means ±20%.

Another Example:

Let’s decode a resistor with the color bands:

  • Brown (1st band)
  • Black (2nd band)
  • Red (3rd band)
  • Gold (4th band)
  1. First Band – Brown: Brown = 1
  2. Second Band – Black: Black = 0
  3. Third Band – Red: Red = multiplier of 100 (10^2 = 100)
  4. Fourth Band – Gold: Gold = ±5% tolerance

Calculation:

  • The first two digits are 1 and 0, so the number is 10.
  • The multiplier is 100, so we multiply 10 × 100 = 1000 ohms.

So, this resistor has a value of 1000 ohms (1kΩ) with a tolerance of ±5%.

5-Band Resistors:

Some resistors have 5 bands, which are used for higher precision. The extra band provides more significant digits for a more precise resistance value.

For 5-band resistors:

  • The first 3 bands represent the first three digits.
  • The fourth band is the multiplier.
  • The fifth band is still the tolerance.

Key Points to Remember:

  • The first two or three bands represent the digits of the resistance value.
  • The third band is the multiplier.
  • The fourth band represents the tolerance (how much the actual value can vary).
  • The color chart helps you identify the corresponding numbers.

Quick Reference for 4-Band Resistor Color Code:

Color Digit Multiplier Tolerance
Black 0 1
Brown 1 10 ±1%
Red 2 100 ±2%
Orange 3 1,000
Yellow 4 10,000
Green 5 100,000 ±0.5%
Blue 6 1,000,000 ±0.25%
Violet 7 10,000,000 ±0.1%
Gray 8 ±0.05%
White 9
Gold ±5%
Silver ±10%

Summary:

  • Resistor color coding is a way to indicate the value and tolerance of a resistor using colored bands.
  • The first two or three bands represent digits of the value, the third band is the multiplier, and the fourth band shows the tolerance.
  • For example, a resistor with the bands Red, Green, Brown, Gold means 250 ohms ±5%.

 

 

 

 

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