Resistor Colour Code

A resistor colour code is a colour marking which translates into a numerical value of the resistor. The marking on the body is in the form of bands, and follows the IEC60062 specifications as defined in their portable document file (PDF). There are two colour code systems currently in use, which include the four-band system, and five-band system. This multi-page article provides calculators, tables, and charts as a quick guide.

5 Band Chart

Here is a five-band chart showing a 1 k resistor colour code as an example. As you can see, it has brown, black, black, and brown bands. The final red band identifies the tolerance ± 2%.

The five-band system provides more precision, as there are three bands dedicated for the significant digits. The fourth band is usually the multiplier, and the fifth band is the tolerance.

However, there are exceptions to this rule, and if the fourth band is gold or silver indicating tolerance, then the third band is the multiplier, and the fifth band becomes the temperature coefficient value.

4 Band Chart

Here is a four-band chart showing a 1 k resistor colour code as an example. As you can see, it has brown, black, and red bands. The final gold band identifies the tolerance ± 5%.

The four-band system is the most commonly used system because it is the easiest to learn in schools, and is usually good enough for hobby use. There are two bands dedicated for the significant digits. The third band is the multiplier, and the fourth band is the tolerance.

3 Band Chart

The three-band chart is the same as a four-band system but without the tolerance band. If you see a resistor and it has no tolerance band, then you read it just as a four-band system, and the tolerance is ±20%.

How to Read

People are often wondering how to read the colour code, and the sad fact is that it is extremely easy. Although at first it might appear difficult, with practice you should be able to decode in your head without using a calculator. Therefore, my advice is not to rely on any calculators for this.

Each colour band represents a numeral, and in a four-band system, the first two bands represent the first two significant digits of the value. The third band represents the multiplier, or the number of zeros to append, and the fourth digit is simply the tolerance information.

In a five-band system, the first three bands represent the significant digits of the value, whilst the fourth band is the multiplier, and the fifth band is the tolerance. The following sections of this page show some examples of how to read resistor colour code. You can treat them as exercises.

Brown, Black, Black, Gold

For example, brown, black, black, gold bands indicate a four-band system. Brown is the first significant digit representing 1, black is the second significant digit representing 0. The second black band represents the multiplier, which is 1. The gold band represents a tolerance of ± 5%. Therefore, the value reads as 10-Ω ± 5%.

1 kΩ – Brown, Black, Red

Here is another example with the following bands brown, black, and red. There is no tolerance band, and therefore it means a tolerance of ± 20%. The brown band represents the first significant digit, which is 1, The black band represents the second digit which is 0. The red band represents the multiplier, which is 100. Therefore, the value reads 1000 Ω ± 20%. This is of course the colour code of a 1 kΩ resistor.

3.3 kΩ – Orange, Orange, Red

In a four-band system, the first two bands are orange representing "33", the third band is the multiplier, which is 100, and therefore the value is 3300 Ω or 3.3 kΩ.

100 ohm – Brown, Black, Brown

The first band represents 1, the second band represents 0, the third band is the multiplier which is 10, thus giving us 100 Ω.

1 ohm – Brown, Black, Gold, Gold

A one ohm resistor has a brown band representing "1", then a black band representing "0" thus representing 10. The third band is the multiplier, which is gold that represents 0.1; therefore, the value is 1 Ω. The fourth gold band is the tolerance, which means ± 5%.

Yellow, Violet, Gold, Gold

Yellow represents 4, violet is 7 thus we have 47 for the first two significant digits. The third band is the multiplier, which is gold that represents 0.1. Therefore, the value is 4.7 Ω. The fourth band is the tolerance, which means ± 5%.

Yellow, Violet, Red

The first band represents 4, the second band represents 7, thus we have 47 for the first two significant digits. The third band (red) is the multiplier, which represents 100. Therefore, the value is 4700 Ω or 4.7 k Ω.

How to Remember

Colours and numbers naturally associate and are very easy to remember, therefore if you can remember them then try to do so without any silly poem or rhymes.

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