color coding of resistance

color coding of resistance

The electronic color code is used to indicate the values or ratings of electronic components, usually for resistors, but also for capacitors, inductors, diodes and others.

Calculating Resistor 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 colour coded bands being read from left-to-right as follows;

Digit, Digit, Multiplier = Colour, Colour x 10 ^colour  in Ohm’s (Ω’s)

For example, a resistor has the following coloured markings;

Yellow Violet Red = 4 7 2 = 4 7 x 10² = 4700Ω or 4k7.

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.
Related Products: Resistor Fixed Single-Other Mounting
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.
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 colour code used to denote the tolerance rating of a resistor is given as;

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

If resistor has no fourth tolerance band then the default tolerance would be at 20%.

It is sometimes easier to remember the resistor colour code by using mnemonics or phrases that have a separate word in the phrase to represent each of the Ten + Two colours in the code. However, these sayings are often very crude but never the less effective for remembering the resistor colours. Here are just a few of the more “cleaner” versions but many more exist:

• Bad Booze Rots Our Young Guts But Vodka Goes Well
• Bad Boys Ring Our Young Girls But Vicky Goes Without
• Bad Boys Ring Our Young Girls But Vicky Gives Willingly — Get Some Now (This one is only slightly better because it includes the tolerance bands of Gold, Silver, and None).

As an added bonus, why not download and make our handy DIY Resistor Colour Code Wheel as a free and handy reference guide to help work out those resistor colour codes.
Related Products: Resistor Fixed Single-Surface Mount