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Lesson on the resistor color code

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Introduction

This lesson explains how to read the color code painted on the bands of the resistors. This information is deliberately brief - but sufficient - because of the many electronic lessons that can be found on the Internet.

In most cases, the resistor is presented with colored rings (bands) around it. Each color corresponds to a digit.

The correspondence between the digits and the colors of the bands is named the resistor color code: this code is used to determine the value of a resistor or indicate its values by using a color code. It is defined by the international standard IEC 60062 entitled "Marking codes for resistors and capacitors".

Example of a resistor (source Wikipedia.org):

Resistor values are standardized and defined by the international standard «IEC 60063» entitled «Preferred number series for resistors and capacitors». These values are classified by series associated with a specific tolerance. The most widely used for consumer electronics is the E24 series (tolerance ±5%): in this series, 24 standard values are defined and for which it is possible to use a multiple of 10 (it is known as «decade»).

Method to read

You must first turn the resistor the right way up. Usually, the resistor has a gold or silver band that must be placed on the right. In other cases, it is the largest band that must be placed on the right or the band placed closest the extremity you must put on the left.

There are three types of resistors depending on the number of bands: 4-band, 5-band and 6-band resistors. Each resistor type is described in the following paragraphs.

4-band resistors

• The first two bands provide significant figures: the first gives the ten and the second the unit.
• The third gives the multiplier, in other words the power of 10 to be multiplied to significant digits (the number of zeros to add to the significant figures).
• The fourth determines the tolerance of the resistor that indicates the incertitude on the effective value of the resistor given by the manufacturer. The selling price of the resistor is inversely proportional to its precision.

Example of a 4-band resistor

• First significant figure: the red color corresponds to the digit 2 (see the correspondence between color and digit in the summary table).
• Second significant figure: the red color corresponds to the digit 2. The significant digits are 22.
• Multiplier: the yellow color corresponds to the digit 4, the significant digits have to be multiplied by 10⁴ (ie. add 4 zeros after the 2 significant figures). The value of the resistor is 220 000 Ω or 220 kΩ.
• Tolerance: the silver color corresponds to the tolerance ±10%. It means that given the incertitude provided by the manufacturer, the effective value of the resistor varies from 198 kΩ (220 kΩ - 220 kΩ x 10/100) and 242 kΩ (220 kΩ + 220 kΩ x 10/100).

5-band resistors

• The first three bands provide the significant figures: the first gives the hundred, the second the ten and the third the unit. The third band is only used when the tolerance of the resistor is less than 2%.
• The fourth gives the multiplier, in other words the power of 10 to be multiplied to significant digits (the number of zeros to add to the significant digits).
• The fifth is the tolerance of the resistor that indicates the incertitude on the effective value of the resistor given by the manufacturer. The selling price of the resistor is inversely proportional to its precision.

Example of a 5-band resistors

• First significant figure: the brown color corresponds to the digit 1 (see the correspondence between color and digit in the summary table).
• Second significant figure: the green color to 5.
• Third significant figure: the black color to 0. The significant digits are 150.
• Multiplier: the orange color corresponds to the digit3, The significant digits have to be multiplied by 10³ (ie. add 3 zeros after the 3 significant figures). The value of the resistor is 150 000 Ω or 150 kΩ.
• Tolerance: the green color corresponds to the tolerance ±0.5%. It means that given the incertitude provided by the manufacturer, the effective value of the resistor varies from 149.25 kΩ (150 kΩ - 150 kΩ x 0.5/100) and 150.75 kΩ (150 kΩ + 150 kΩ x 0.5/100).

6-band resistors

• The first five bands have the same meaning as the 5-band resistors (see above).
• The sixth band is a temperature coefficient that indicates the change in electrical conductivity with temperature.

Example of a 6-band resistor

• First significant figure: the orange color corresponds to the digit 3 (see the correspondence between color and digit in the summary table).
• Second significant figure: the black color to 0.
• Third significant figure: the red one to 2. The significant figures are 302.
• Multiplier: the red color corresponds to the digit 2: the significant digits have to be multiplied by10² (ie. add 2 zeros after the 3 significant figures). The value of the resistor is 30 200 Ω or 30.2 kΩ.
• Tolerance: the green color corresponds to the tolerance ±0.5%. It means that given the incertitude provided by the manufacturer, the effective value of the resistor varies from 30.049 kΩ (30.2 kΩ - 30.2 kΩ x 0.5/100) and 30.351 kΩ (30.2 kΩ + 30.2 kΩ x 0.5/100).
• Temperature coefficient: the blue color corresponds to a temperature coefficient equal to 10 ppm/°C.

Summary table

The following printable summary table will allow you to have the resistor color code within reach, in addition to the software Atlence Resistor Viewer.

Note : The 3^rd band (3^rd significant digit) is only used when the tolerance of the resistor is less than 2%.

List of the 24 normalized values in the E24 series:

10	11	12	13	15	16	18	20	22	24	27	30
33	36	39	43	47	51	56	62	68	75	82	91

Test your skills

To practice and test your knowledge on the resistor color code, download Atlence Resistor Viewer: it includes a quiz on the resistor color code.

Tip

A mnemonic to keep in mind the resistor color code is to remember one of the following two sentences:

Bad Beer Rots Our Young Guts But Vodka Goes Well

or

Black Bears Rarely Outrun Young Grizzlys But Victimize Gray Wolves

By taking the first letter of each word, you get the color:

1st letter	Color	Position
B	Black	0
B	Brown	1
R	Red	2
O	Orange	3
Y	Yellow	4
G	Green	5
B	Blue	6
V	Violet	7
G	Gray	8
W	White	9

The position of the words in the sentence (by starting the numbering at 0) indicates the digit that corresponds to the color of the band.