Resistor color code and how it works

Let me tell you about the resistor color code, how it works, and Standard resistor values. 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

My daughter asked, “Why do you need a resistor?” The resistors will resist the flow of electricity. Also, we can use them a lot. For example,

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. It can be difficult to see resistor values on them. So, these resistors have color-coded instead.

Resistor color code calculator

To begin with, look at the block diagram below. Now, most resistors have 4 color bands. It will have the same color for 0.25 watts, 0.5 watts, 1 watts, and 2 watts. When I was a young boy. I used to see the three color bands on AM receiver radio.

How to find resistor color code

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

Secondly, start to look at the color band from left to right. The first is the first digit of the 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 use, its resistance is between 950Ω  and 1050Ω.

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

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

How to read resistor color code without calculating

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 not understand how to use it.  When more used more understand!

For example, You have 6 resistors. The last color band is Glod. So, it is a 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 the 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 colors. 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 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 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 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 Silver, we put the dot font in 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 table 5% tolerance

The following are the standard resistor values table 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 8.2MΩ
  0.5Ω  0.22Ω 0Ω

Standard resistor values 5% tolerance
Standard resistor values 5% tolerance

OR you can look list of color codes on each resistor here.

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

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 values. This ideal is the cheapest that uses 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 copper alligator clips to connect 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 2.2 ohms resistors. Just connects in series with the 3 ohms resistors only.

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


I always try to make Electronics Learning Easy.

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7 thoughts on “Resistor color code and how it works”

  1. 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.


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