Resistor Colour Coding: What It Is, How to Read It, and Where It Is Used

A resistor is an electrical component that limits or regulates the flow of electrical current in an electronic circuit. Resistors can also provide a specific voltage for active devices such as transistors, making them fundamental building blocks in virtually all electronic equipment.

The challenge with resistors is their size. Most resistors are too small to print numerical values on them legibly. To solve this problem, the Radio Manufacturers Association (RMA) developed a colour coding system in the 1920s that uses coloured bands painted on the resistor body. This system was later standardised internationally and is now defined by IEC 60062 (IEC, 2016).

The resistor colour code assigns each colour a numerical value from 0 to 9, plus additional meanings when used as multiplier or tolerance bands. The standard colour sequence follows a specific order that many engineers memorise using mnemonics.

If a resistor has no tolerance band, the default tolerance is ±20%. Most four-band resistors have tolerances of 5%, 10%, or 20%, while five-band precision resistors typically offer 1% or 2% tolerance.

Reading resistor colour codes correctly requires understanding the band positions and their meanings. The most common configuration is the four-band resistor, though five and six-band variants exist for higher precision applications.

Four-Band Resistors

The most common resistor type uses four coloured bands. The first band (nearest the lead) indicates the first significant digit, the second band indicates the second significant digit, the third band is the multiplier, and the fourth band shows tolerance.

1. 1

   Identify the First Band

   Position the resistor so the band closest to a lead is on the left. This is your first significant digit. A gold or silver band is always the tolerance band and should be on the right.

2. 2

   Read Left to Right

   Read the first two bands as significant digits (for four-band) or first three bands (for five-band). These give you the base number.

3. 3

   Apply the Multiplier

   Multiply your base number by the multiplier value to get the resistance in Ohms (Ω). The multiplier tells you how many zeros to add.

4. 4

   Note the Tolerance

   The final band indicates how much the actual value may vary from the stated value. A gold band means ±5%, silver means ±10%.

Worked Example

Consider a resistor with bands: Blue, Grey, Black, Red. Using the colour code chart: Blue (6), Grey (8), Black (×1), Red (±2%). The calculation is 68 × 1 = 68Ω with ±2% tolerance. For a more complex example, Blue, Grey, Red, Gold would be: 68 × 100 = 6,800Ω (6.8kΩ) with ±5% tolerance.

While the resistor colour code was developed for electronic components, its application extends far beyond circuit boards. The broadcast, audio, and live events industries have adopted this colour coding system for cable identification, using the familiar colour sequence to identify cable channels, lengths, and signal paths.

Why Broadcast Uses Resistor Colour Coding

The resistor colour code has been used by broadcast designers and installers for many years because it provides a standardised, universally recognised system. When engineers work across different facilities or with equipment from various manufacturers, the consistent colour coding allows them to quickly identify cable idents at a distance without referring to documentation.

In audio snakes and multi-channel installations, cables are typically colour coded following the resistor sequence: brown for channel 1, red for channel 2, orange for channel 3, and so on. This makes it possible to trace cables through complex routing systems and identify connections at both ends rapidly.

Traditional Application Methods

Traditionally, individual coloured ferrules are used to apply resistor colour coding to cables. Each coloured ferrule is threaded onto the cable to create the identification pattern. While effective, this approach has significant drawbacks on larger projects. Applying individual ferrules is time-consuming, and installers must maintain stock of all required colours to complete any given job. For installations with hundreds or thousands of cable identifications, the labour cost of manual ferrule application can become substantial.

Silver Fox® is the only company to provide resistor colour coding functionality in its labelling software. This capability was introduced in 2008, recognising that broadcast and audio engineers needed a faster way to produce colour coded cable identification while maintaining industry standards.

The resistor colour code functionality is available in the Advanced and Professional levels of Labacus Innovator® software. Rather than threading individual ferrules onto each cable, engineers can design and print complete colour coded labels in a fraction of the time.

Best Label Types for Colour Coded Applications

For resistor colour coded cable identification, Prolab® Laser Wrap Around labels are particularly well suited. These self-laminating labels wrap around the cable, making the identification visible from all angles. This is especially useful for maintenance and repair situations where terminated cables need labelling, or where the cable ident must be readable regardless of how the cable lies in a tray or bundle.

Using a colour laser printer with Labacus Innovator® Advanced or Professional software, you can print the resistor colour bands directly onto the labels. The printed result replicates the visual appearance of ferrule-based colour coding while offering additional space for text identification alongside the colour bands.

How do you label cables using resistor colour coding?

Traditionally, coloured ferrules are threaded onto cables in sequence to create the identification pattern. With modern labelling solutions like Labacus Innovator® software, you can print the colour bands directly onto wrap around or tie-on labels, achieving the same visual result in far less time. For more on cable labelling methods, see our guide to labelling terminated wires.

What software level do I need for resistor colour coding?

Resistor colour code functionality requires Labacus Innovator® Advanced or Professional level. You will also need a colour laser printer to produce the coloured bands. The Basic level does not include this feature, though it handles standard text-based cable labelling effectively.

Can I combine colour coding with other identification methods?

Yes. Using Labacus Innovator® Professional, you can add barcodes, QR codes, and graphics alongside resistor colour coded bands. This allows you to maintain traditional visual identification while also enabling digital asset management and traceability. Learn more about barcode and QR code labelling.

Which industries use resistor colour coding for cables?

Broadcast television, radio stations, live event production, recording studios, and audio-visual installation companies commonly use resistor colour coding. The system is also used in some industrial control applications where visual channel identification is preferred over text-only labels.

How does printed colour coding compare to individual ferrules?

Printed labels offer significant time savings compared to threading individual ferrules. On a typical project, applying 50 cable identifications using printed labels takes approximately 5 minutes including design time, versus potentially several hours using manual ferrules. The printed approach also eliminates the need to maintain stock of multiple ferrule colours.