Resistors are available in many different values and the colour bands on them are used to indicate what value the resistor is. Looking at this resistor, you will see there are four coloured bands. Although you can get resistors with 5 bands, these tend to be for higher tolerance resistors, we are only going to consider the 4 band version.

 There are ten different colour bands, with a different colour being used for each of the numbers 0 to 9.  If you are going to be able to work our the value of a resistor you need to have learnt the number that go with each colour (or at least have this information to hand).  The colour values are shown below, so if for example we need a value 2 red is used.

Tolerance  When you are looking at real resistors, the first thing you will need to do is make sure they are the right way around to read. In school you are only likely to use resistors which have a 5% tolerance. This is indicated by the right most band being gold. If the resistor you are looking at has the gold band on the left edge turn it so it is on the right.

Value and Zeros  The first two bands on the resistor indicate the value. With the third band showing the number of extra zeros. So looking at the example (below) there is a brown & green band from the colour codes explained earlier brown, green = 15. The black band (value zero), tells us there are no extra zeros. Thus the resistor shown is a 15 ohm resistor.

 Lets look at another example. This resistor has a value of yellow (4), purple (7), with brown (1) extra zero. So it's 47 with 1 extra zero, making it a 470 ohm resistor.

 This is the final example, the bands are: red (2), red (2) orange (3). 22 with 3 extra zeros, a 22,000 R resistor.  Writing lots of zeros is unnecessary, as there are abbreviations for 000 and 000,000.  1,000 ohms = 1 Kilo ohm (or K) 1,000,000 ohms = 1 Meg ohm (or M)  So we can say that the resistor is a 22K resistor.

 Now it's your turn. Look at the resistor shown left and work out what value you think it is. (Go to next slide to check your answer).

Answer  If you decided it's 6,800R resistor, well done. An extra bonus mark for you if you worked out that it could be better written as a 6.8K resistor.  If you return to the interactive learning & test zone you can test yourself on resistor colour bands.