Resistor Colour Codes Explained

Common Resistor

Resistors are colour coded for easy reading. Imagine how many blind technicians there would be otherwise.

To determine the value of a given resistor look for the gold or silver tolerance band and rotate the resistor as in the photo above. Tolerance band to the right). Look at the 1st colour band and determine its colour. This maybe difficult on small or oddly coloured resistors. Now look at the chart and match the "1st & 2nd colour band" colour to the "Digit it represents". Write this number down.

Example:

Now look at the 2nd colour band and match that colour to the same chart. Write this number next to the 1st Digit.

The Last colour band is the number you will multiply the result by. Match the 3rd colour band with the chart under multiplier. This is the number you will multiple the other 2 numbers by. Write it next to the other 2 numbers with a multiplication sign before it. Example : 2 2 x 1,000.

To pull it all together now, simply multiply the first 2 numbers (1st number in the tens column and 2nd in the ones column) by the Multiplier.

Tolerance Explanation

Resistors are never the exact value that the colour codes indicate. Therefore manufacturers place a tolerance colour band on the resistor to tell you just how accurate this resistor is made. It is simply a measurement of the imperfections. Gold means the resistor is within 5% of being dead-on accurate. Silver being within 10% and no colour band being within 20%. To determine the exact range that the resistor may be, take the value of the resistor and multiply it by 5,10, 0r 20%. That is the number that the resistor may go either way.

Example: A 1,000 Ohm resistor with a gold band maybe any value between 950 to 1050 Ohms.

Example: A 22,000 Ohm resistor with a silver band maybe any value between 19,800 and 24,200 Ohms.

FAQ

Just a few common questions to help you out.

1) Which side of the resistor do I read from?

The Gold or Silver band is always set to the right, then you read from left to right. Sometimes there will be no tolerance band -- Simply find the side that has a band closest to a lead and make that the first band.

2) Sometimes the colours are hard to make out. How do I make certain what the value of the resistor really is?

Occasionally the colours are jumbled or burnt off. The only way to read it then is with a multimeter across the leads

3) How do I remember this sequence of colours?