How to read the resistor value through the colored line

The colored line on the resistor is a way to help you read the correct value of that resistor. So how do you read the resistor value through the colored line? The following article will guide you on how to calculate and read the value of the resistor using the most accurate color line.

What is resistance?

Resistor is an essential passive electronic component, often appearing in electrical circuits with the symbol R. The outstanding feature of the resistor is the colored lines on the body. This colored line helps the user read the value of that resistor.

The main effect of the resistor is to customize the current through the load accordingly. In addition, resistors can also generate heat in applications where it is needed or regulate the amperage through electrical devices.

How are the resistor values calculated?

Instructions for calculating resistor values based on the color chart

Usually, the manufacturer will print the value on the outside of the resistor. But you can also read the value of the resistor through the color convention as follows:

Instructions on how to read the resistor value in four color bars

The resistor value reading for a 4-bar color resistor is as follows:

• The first colored line represents the 10-value.
• The second colored line represents the unit value.
• The third colored line represents the multiplier for the exponent value of ten.
• The fourth colored line represents the resistor’s error value. Because the fourth ring is always gold or silver, its value can be ignored when reading.

The following formula can be used to determine resistance value: × 10 of (color bar 1), (color bar 2) (bar cap 3)

For instance: on a resistor with red, yellow, brown, and golden colored lines, respectively, the first line is valued at 2, and the second line is valued at 4. The third line has a value of 1, and the fourth line is empty.

The value of the resistor in the above case is 24 x 10^1 = 240(Ω)

Instructions on how to read the resistor value 5 color bars

The reading of the resistor value for the colored 5-bar resistor is as follows:

• The hundreds value is represented by the first colored line.
• The tens value is represented by the second colored line.
• The unit value is represented by the third colored line.
• The multiplier for the exponent value of 10 is represented by the fourth colored line.
• The resistor’s error value is represented by the fifth colored line.

The following formula can be used to determine the resistance value: 

(color line 1)(color line 2)(color line 3) x 10^color line 4 + color line 5

For example: if the colored lines on the resistor are brown, red, orange, yellow, and red, respectively, then the first line has a value of 1, the second line has a value of 2, the third line has a value of 3, and the fourth line has a value of 4. The value of the fifth line is 2%.

So the value of the resistor in the above case is 123 x 10^4 ± 2% = 1230000±2%

How should power resistor values be read?

Resistors with a capacity of more than 1W, 2W, 5W, or 10W are referred to as power resistors. It is frequently utilized in circuits with high current flows.

The process for reading a power resistor value is similar to that for reading a standard resistor value.

What is the difference between practical value and theory?

Although the actual measured value won’t be entirely exact, it will be within the resistor’s tolerance.

For example 300 resistor with 5% tolerance

We calculate the tolerance range as follows: 300×5%=15 (Ω)

Hence, the observed value for a 300 resistor with a 15% tolerance falls within the range [285,315]

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How to determine the reading direction of resistor color lines

Looking at the resistor, you will see that there is one colored line that is further away from the remaining colored lines. That is the final color line. Based on this, you will find the first colored line.

Above is how to calculate and read the resistor value through the colored line. Hopefully, through this article, everyone has been able to calculate and read the correct resistor value. For all information about solder flux, solder paste, etc., please contact The tech for the best advice!