From Bands to Values: How to Read the Resistor Color Code

Resistors are a key component in electronic circuits, controlling the flow of electrical current. Resistors are available in many different values, shapes, and physical sizes. Practically all leaded resistors with a power rating up to two watt have this pattern of colored bands. Color bands on the body of a resistor, carry crucial information about their resistance value, tolerance, and sometimes even the temperature coefficient.

A resistor can have anywhere from three to six colored bands, with four bands being the most common. The first bands typically indicate digits in the resistance value, followed by a multiplier band to adjust the decimal position. The final bands show the tolerance level and temperature coefficient. See our new article on detailed description of different electronic devices.

What Is the Resistor Color Code?

The resistor color code is a standardized system that uses colored bands on the resistors itself to represent its resistance value and  tolerance. Each color corresponds to a number, which helps determine the resistor's resistance in ohms (Ω). Reading resistor color codes is easy once you understand the meaning and the math behind each band. Here is a simple chart explaining resistor color code detail:

4-Band Resistor Color Code:

The first two bands on a 4-band resistor represent the first and second digits of the resistance value. The third band represents the multiplier, and the fourth band represents the tolerance.

In a general 4 band resistor the color code followed as:

• First Band (Digit 1): Represents the first significant digit of the resistor's value.
• Second Band (Digit 2): Represents the second significant digit.
• Third Band (Multiplier): Tells you the factor by which the first two digits should be multiplied.
• Fourth Band (Tolerance): Indicates how accurate the resistor's value is, typically showing how much it can deviate from its nominal value.

Here is a saying which represents the first letter of color, for remembering the color code easily.

BB ROY GREAT BRITAIN VERY GOOD WIFE WEARING GOLD SILVER NECKLACE

Calculating Resistor Colour Code Values:

The Resistor Colour Code system is all well and good but we need to understand how to apply it in order to get the correct value of the resistor. The “left-hand” or the most significant coloured band is the band which is nearest to a connecting lead with the color coded bands being read from left-to-right as follows:

Digit-1, Digit-2, Multiplier = Colour, Colour x 10 color in Ohm’s (Ω).

For example, a resistor has the following coloured markings:

Yellow Violet Red = 4 7 2 = 4 7 x 10^2 = 4700Ω or 4k7 Ohm.

The fourth and fifth bands are used to determine the percentage tolerance of the resistor. Resistor tolerance is a measure of the resistors variation from the specified resistive value and is a consequence of the manufacturing process and is expressed as a percentage of its “nominal” or preferred value.

Example of a 1K Resistor:

Let's say you have a resistor with the following color bands: Brown, Black, Red, Gold.

• First Band (Brown): 1
• Second Band (Black): 0
• Third Band (Red, multiplier): 100
• Fourth Band (Gold, tolerance): ±5%

To calculate the resistance, you combine the first two digits (10) and multiply them by the multiplier (100), resulting in a 1,000Ω (1kΩ) resistor with a tolerance of ±5%.

5-Band Resistor Color Code:

Resistors with high precision have an extra color band to indicate a third significant digit. The first three bands on a 5-band resistor represent the first, second, and third digits of the resistance value. The fourth band represents the multiplier, and the fifth band represents the tolerance.

Calculate the resistance value using the following formula:

Resistance (Ω) = (1st digit value x 100 + 2nd digit value x 10 + 3rd digit value) x Multiplier

Lastly, determine the tolerance by identifying the fifth band’s color.

6-Band Resistor Color Code:

A six-band resistor is basically a five-band type with an additional ring indicating the reliability, or the temperature coefficient (ppm/K) specification. The first three bands on a 6-band resistor represent the first, second, and third digits of the resistance value. The fourth band represents the multiplier, the fifth band represents the tolerance, and the sixth band represents the temperature coefficient.

Calculate the resistance value using the following formula:

Resistance (Ω) = (1st digit value x 100 + 2nd digit value x 10 + 3rd digit value) x Multiplier

Next, determine the tolerance by identifying the fifth band’s color. Finally, determine the temperature coefficient by identifying the sixth band’s color. The temperature coefficient represents the resistor’s change in resistance as the temperature changes.

Why the Tolerance Matters:

Tolerance indicates how much the resistor's actual value may differ from its standard value. For instance, a 1kΩ resistor with ±5% tolerance can vary between 950 Ω and 1,050 Ω. Tolerance is crucial when precision is needed in sensitive circuits. Typical resistor tolerances for film resistors range from 1% to 10% while carbon resistors have tolerances up to 20%. Resistors with tolerances lower than 2% are called precision resistors with the or lower tolerance resistors being more expensive. If the resistor has no fourth tolerance band then the default tolerance would be at 20%.

Most five band resistors are precision resistors with tolerances of either 1% or 2% while most of the four band resistors have tolerances of 5%, 10% and 20%. The color code used to denote the tolerance rating of a resistor is given as:

Brown = 1%, Red = 2%, Gold = 5%, Silver = 10 %

What is a “Reliability” Band?

Military-grade resistors often have an additional band on four-band resistors to indicate reliability, or the failure rate (%) per 1,000 hours of operation. This feature is rarely used in commercial electronics.

What is a Zero-ohm Resistor?

Zero-ohm resistors, identifiable by their single black band, serve as simple wire links connecting traces on a PCB. Packaged like resistors, they allow the same automated equipment used for resistor placement to also place these links, eliminating the need for a separate machine to install jumper wires. To know more about electronics components and their usagae explore our blogs, see our detailed article on capacitor and its types.

Conclusion:

Reading the resistor color code may seem tricky at first, but once you memorize the color-to-number association through the given processes. Many people find it easier to remember the resistor color code using a mnemonic rhyme that corresponds to each color's digit as mentioned in the color code section above. Whether you're a hobbyist or a professional, mastering this skill is essential for designing and troubleshooting circuits with confidence. Now you are ready to jump and repair a system which contains a lot of different resistors.