Figure 1
Each digit is encoded in colour according to the following chart:
Digit Colour
------------
0 Black
1 Brown
2 Red
3 Orange
4 Yellow
5 Green
6 Blue
7 Violet
8 Grey
9 White
A series of coloured bands around the body of the resistor specifies the amount of resistance and the tolerance. To read the code, begin at the end of the resistor where the closest band appears. Figure 1 gives the idea:
The most common tolerances are 10% (silver) and 5% (gold). A tolerance of 20% is also possible. In this case, the fourth band is missing.
Suppose the coloured bands follow the pattern red, violet, orange, gold. The first three bands give the resistance as
2 (red)
7 (violet)
3 (orange)
or 27000 ohms (27k ohms). The fourth band specifies a tolerance of 5%.Not all combinations of colours will be found, since manufactures generally offer only an assortment of values. For 5% and 10% tolerances, twelve values are common. These are listed below, along with the colour of the first two bands:
Value 1st Band 2nd Band
-----------------------------
10 Brown Black
12 Brown Red
15 Brown Green
18 Brown Grey
22 Red Red
27 Red Violet
33 Orange Orange
39 Orange White
47 Yellow Violet
56 Green Blue
68 Blue Grey
82 Grey Red
Note. The above discussion does not pertain to precision resistors (1% or better), which usually contain five bands.