Many people who are just getting into electronics often feel curious and confused when they see those tiny components on a circuit board with colorful rings on them. So, what exactly are these colored rings? Actually, they are the marking system on resistors used to show resistance value and tolerance. This system is called the resistor color code. Learning how to read it is one of the very first steps into the world of electronics. With just a glance, and without any measuring tools, you can tell the resistance value.

There are many ways to measure resistance, like using a multimeter or the volt-ampere method. The volt-ampere method (also known as the voltmeter-ammeter method) is quite common. It's based on Ohm's rule: R = U / I, meaning you divide voltage by current to get resistance.

But for the most common color ring resistors, you don't need to measure — you can calculate it directly. The color code system is mainly used on cylindrical resistors, such as carbon film resistors, metal film resistors, metal oxide film resistors, fuse resistors, and wire-wound resistors. These resistors use four, five, or six colored rings to represent their value.

Catalog

I. What is a Color Code Resistor?

II. Resistor Color Code Chart

III. How to Read a Four-Band Resistor?

IV. How to Read a Five-Band Resistor?

V. How to Read a Six-Band Resistor?

VI. Summary

I. What is a Color Code Resistor?

Color code resistors are some of the most widely used components in electronic circuits. To make resistance values easy to identify, resistors are painted with colored bands on their casing. This design ensures that no matter which way you install the resistor, you can easily read its value.

The basic unit is the ohm (Ω). Larger units include kilo-ohm (KΩ) and mega-ohm (MΩ), where 1 mega-ohm equals 1000 kilo-ohms, or 1,000,000 ohms.

The most common ones you'll see are four-band resistors and five-band resistors, with four-band being more widely used.

· Four-band resistors: The first two bands represent significant digits, the third band is a multiplier (like adding zeros), and the fourth band shows tolerance.

· Five-band resistors: The first three bands represent significant digits, the fourth band is the multiplier, and the fifth band shows tolerance. These usually have higher precision.

· Six-band resistors: On top of the five-band system, the sixth band represents the temperature coefficient. These are rare and used only when precise temperature requirements are involved.

Tolerance colors are usually gold, silver, and brown. Gold means ±5%, silver ±10%, and brown ±1%. If there's no band, tolerance is ±20%. Sometimes green appears, meaning ±0.5%.

In the early days, resistor color codes were essential because resistors were larger. But in today's highly integrated circuits, color-coded resistors are used less often.

II. Resistor Color Code Chart

To decode the color bands, you need to memorize the relationship between colors and numbers. With the chart, you can easily determine a resistor's value and tolerance. You can also use an automatic resistor calculator to speed things up.

Here's a simple rhyme to help remember: Better Be Right Or Your Great Big Venture Goes West.

Now for the numbers: Black is 0, Brown 1, Red 2, Orange 3, Yellow 4, Green 5, Blue 6, Violet 7, Grey 8, and White is 9. Gold means 5% tolerance, and Silver 10%.

III. How to Read a Four-Band Resistor?

A four-band resistor uses four colored bands to show its value. As shown in the image above, reading from left to right: the first band is the first significant digit, the second band is the second significant digit, the third band is the multiplier, and the fourth band is the tolerance (accuracy). The key to reading it is finding the first band. For four-band resistors, the last band (tolerance) is usually gold or silver, colors rarely used for the other bands.

For example, the 4-band resistor in the image above has the colors: grey, red, orange, gold.

· First band (Gray): digit 8

· Second band (Red): digit 2 (So, the base number is 82)

· Third band (Orange): multiplier 1,000 (This means you multiply the base number by 1000)

· Fourth band (Gold): Tolerance ±5%

So, this resistor's value is 82 x 1,000 = 82,000 Ω = 82 kΩ, with a tolerance of ±5%.

IV. How to Read a Five-Band Resistor?

A five-band resistor uses five colored bands. Reading it is similar, but it has one more significant digit, offering higher precision. As shown above, from left to right: the first band is the first significant digit, the second is the second digit, the third is the third digit, the fourth is the multiplier, and the fifth is the tolerance. Its tolerance band is usually brown, red, gold, or silver, but the colors can vary more, so check the chart carefully.

For example, the 5-band resistor above has the colors: green, red, brown, black, brown.

· First band (Green): digit 5

· Second band (Red): digit 2

· Third band (Brown): digit 1 (So, the base number is 521)

· Fourth band (Black): multiplier 10? = 1 (So, 521 x 1 = 521)

· Fifth band (Brown): Tolerance ±1%

So, this resistor's value is 521 Ω, with a tolerance of ±1%.

This is a relatively precise resistor. In circuits, a 521Ω value is often found in precision voltage dividers, feedback circuits, or as a current-limiting resistor for specific components. The ±1% tolerance means its actual resistance will be between 515.79Ω and 526.21Ω (521 ± 5.21).

V. How to Read a Six-Band Resistor?

A six-band resistor uses six colored bands. The first five bands are read just like a five-band resistor. The sixth band indicates the resistor's temperature coefficient (ppm/°C = ppm/K). The most common color for the sixth band is brown (100 ppm/°C). This means for a 10°C temperature change, the resistance can change by 1000 ppm = 0.1%. Six-band resistors are only used in specific applications and are pretty rare.

For example, the 6-band resistor above has the colors: orange, red, brown, brown, brown, red.

· First band (Orange): digit 3

· Second band (Red): digit 2

· Third band (Brown): digit 1 (So, the base number is 321)

· Fourth band (Brown): multiplier 101 = 10 (So, 321 x 10 = 3,210 Ω = 3.21 kΩ)

· Fifth band (Brown): Tolerance ±1%

· Sixth band (Red): temperature coefficient 50 ppm/°C

So, this resistor's value is 3.21 kΩ, with a tolerance of ±1% and a temperature coefficient of 50 ppm/°C.

This is a very high-precision (±1%), stable (low drift) resistor, commonly found in precision instruments, communication equipment, and other applications demanding high circuit performance.

VI. Summary

Even though modern circuit boards mostly use tiny SMD resistors instead of through-hole color-coded ones, knowing how to read resistor color codes is still an essential skill for beginners and repair work.

Next time you see a resistor, pick it up and try reading the color bands. With a bit of practice, you’ll be able to crack these colorful codes easily — and know the resistance value without ever measuring it.