Resistor color code and how it works

Let me tell you about resistor color code and how it works. We often look at a lot of resistors in many electronic circuits.

Do you know how to use it? How it works. I think it is a very important electronic device. If you do not have them. Your project may not work.

What is a resistor

The resistor is an electronics component. Meet Resistors in the image below.

The popularly used Resistor

It looks like a beautiful worm. With 2 legs on the head and end of the body. The 1/4 watts resistor is my most used shape.

And, Look at the symbol here.

Resistor Circuit Symbol

What does a resistor do

It will resist or limit the current flowing it. The levels or size that they are resisting. We call the resistance.

If more resistance, less current flows in the circuit. You may not imagine. The current looks like the water in a pipe, below.

What does a resistor do
  • The left resistor has high resistance. So the current can flow is low.
  • But on the other hand, the right has low resistance inside. So the current can flow through it higher.

Many ways to use them

Resistors resist the flow of electricity. Also, we can use them a lot. For example,

  • Using the resistor in a series circuit.
  • They are very useful for reducing the current to the LED. Which it can damage with too much current.
  • Most using resistors to divide a voltage into a smaller voltage.
  • Resistors are used to increase the time required to charge capacitors and speed up the discharged of capacitors.
  • They are also used to control the gain of amplifiers.

Learn the resistor

When my son learns about basic Electronics. He should learn about the resistors first.

kid learn measure resistors

Today we will learn about the resistors

  1. How does it shape? He said they look like a worm.
  2. Learn to use the meter to measure its value. Now, I have not taught him to read the color code. Because it is too difficult for him. He uses a digital ohmmeter to measure the resistors. It is so easy to read the resistance of the resistors.
Basic learn resistor ohms symbol

Then, he learns about basic of resistor, name, symbol and Its value in decimal units.

Learn more: Electronics circuit symbols

Learns resistor symbol decimal math in electronic

What to expect him to get

  • Drawing skills
  • Using a digital multimeter to measure the resistors or how to use ohms meter.

Learn math in Electronics
He has not understood the math (decimal point). But it is important in Electronics. He can understand in the future.

Resistor color code

When we look at the resistor. We will notice many color bands on it. These colors show their resistance. We can measure them in ohms. When we write it, we can write an omega symbol, Ω.

1Ω is quite small so resistor values are often given in kΩ and MΩ.

For example,

1kΩ =1,000Ω
10kΩ = 10,000Ω
100kΩ = 100,000Ω
1MΩ =1,000,000Ω.

Why use color codes? As the resistors are small components. We can difficult to see resistor values on them. So, these resistors have the color-coded instead.

Resistor color code calculator

To begin with, you look at the block diagram below. Now, most resistors have 4 color bands. When I was a young boy. I used to see the three color bands in AM receiver radio.

How to find resistor color code

Suppose we have a resistor color code, brown, black, red and gold. How many its resistance?

Secondly, start to look the color band left to right. The first is the first digit of resistance. We know the first band is “1” in resistance.

Then, the second band is the second digit. It is black for “0”.

Now, we have the resistance is 10.

Look at the third color band is red. The multiplier is 100Ω.

So, the resistance is 10 x 100Ω or 1kΩ

The fourth color band means an actual resistance, tolerance. It is gold, so its tolerance of ±5 percent, 25Ω.

Thus in real using its resistance is between 950Ω  and 1050Ω.

Which if you see the resistors having the tolerance resistance 10%(silver). You can get it is the same this how.

Look at the resistor again. You will notice two group color. First, tolerance is one band only, often for gold. Second, three bands are the resistance value.

How to read resistor color code without calculate

My son does not like to use how above. He finds an easier way.
Without calculate Decode resistor color code
We can decode the resistor color without having to calculate with this table.

You may do not understand how to use it.  When more use more understand!

For example, You have 6 resistors. All last color band is Glod. So, it is 5% tolerance. What is each resistance?

1. The first resistor,—Brown, Black, Red, and Gold.  First, Brown and Black are 10.  Second, look at the third color band is red. We put a dot between the first color and second color band. It is 1.0. Then we put a kΩ as its unit.  Now we have 1.0kΩ or 1kΩ.

2. The second resistor,—Yellow, Purple, Red, and Gold. First, yellow and purple are 47.  Then, we put the dot between the first and second color. It is 4.7. Next, we put the kΩ.  So its resistance is 4.7kΩ.

3. Third resistor,—Orange, Orange, Orange, Gold.  First, yellow and purple are 33.  Then, we put a kΩ at behind the second color as the unit. So its resistance is 33kΩ.

4. Fourth resistor,—Red, Red, Yellow, Gold.  First, Red and Red are 22.  Then, we put 0 (zero) behind the second color. It is 220. Next, put a kΩ at behind the zero as the unit. So its resistance is 220kΩ.

5. Fifth resistor,—Brown, Black, Gold, Gold.  First, Brown and Black are 10.  When the third color band is the Gold, we put the dot between the first color and second color band. It is 1.0 and the unit is Ω.  So, the resistance is 1.0Ω or 1Ω.

6. Sixth resistor,—Green, Black, Silver, and Gold. First, Green and Black are 50.  When the third color band is the Silver, we put the dot font the first color band. It is 0.50 and the unit is Ω.  So, the resistance is 0.50Ω or 0.5Ω.

Standard resistor values 5% tolerance

The following are the standard resistor values available in carbon film with  5
percent tolerance.

 10Ω 100Ω
 3.3Ω 33Ω 330Ω
 3.6Ω 36Ω 360Ω
 3.9Ω 39Ω 390Ω
 4.3Ω 43Ω 430Ω
 4.7Ω 47Ω 470Ω
 5.1Ω 51Ω 510Ω
 5.6Ω 56Ω 560Ω
 6.2Ω 62Ω 620Ω
 6.8Ω 68Ω 680Ω
 7.5Ω 75Ω 750Ω
 8.2Ω 82Ω 820Ω
 9.1Ω 91Ω 910Ω
1kΩ 10kΩ 100kΩ
 3.3kΩ 33kΩ 330kΩ
 3.6kΩ 36kΩ 360kΩ
 3.9kΩ 39kΩ 390kΩ
 4.3kΩ 43kΩ 430kΩ
 4.7kΩ 47kΩ 470kΩ
 5.1kΩ 51kΩ 510kΩ
 5.6kΩ 56kΩ 560kΩ
 6.2kΩ 62kΩ 620kΩ
 6.8kΩ 68kΩ 680kΩ
 7.5kΩ 75kΩ 750kΩ
 8.2kΩ 82kΩ 820kΩ
 9.1kΩ 91kΩ 910kΩ
2.7MΩ 8.2MΩ0.5Ω
Standard resistor values 5% tolerance
Standard resistor values 5% tolerance

OR you can look list color code on each resistor here.

What is more? Sometimes you cannot find a resistor. You may use this way to do.

DIY Cheap Resistance Decade Circuit

Here is a DIY resistance decade tool for testing and calibration. Because it can substitute into a circuit with all standard value. This ideal is cheapest that use resistors and wires only.

In each experiment, a resistor needs to involve at all times, and is Often unable to find the required resistance. This problem will solve with the “DIY Cheap Resistance Decade Circuit”.

How it works

This variable resistor is not “the normal potentiometer”. It is a very high accuracy and tolerates low current. We need a “decade resistor” in the image below.

The way it works is very simple, is organized as a series resistor. The first set resistors have four resistors include with 1, 2, 3 and 6 ohms. The set 2 and 3 to series will add value up 10 times and 100 times is 10, 20, 30, 60, 100, 200, 300, 600 in sequence. As shown in Figure 2

DIY Cheap Resistance Decade Circuit
DIY Cheap Resistance Decade Circuit

How to application

For example, resistance is 39 ohms. Use a copper alligator clips to connected the resistors 3, 6 and 30 ohms in series as Figure 2. And If you Require the resistances as a decimal fraction. Such as the 5.2 ohms. But we have a 2.2 ohms resistors. Just connects in series with the 3 ohms resistors only.

The advantages of this decade resistors are cheap. Select the desired setting is simple and accurate. Without using the meter to adjust the resistance. Tolerate high current (Depending on power tolerate rate that you’re using). The disadvantage is that the Wasted space If the installation is not good, it makes the resistor shorted together.

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I always try to make Electronics Learning Easy.


  1. Lamont Flores

    I have to thank you for your I am getting older and have very little education your article on lm317has made it simple to understand
    Much respect to you sincerely

    • Hi Lamont,
      I am always happy. When the elderly said Interested in learning electronics. It makes our lives useful. Time passed quickly and everyone enjoyed. Also, the children liked it.

      I will dedicate to writing the easiest readable articles.

  2. rirei

    It is good teaching! so easy to learn. Keep your job!

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