The Resistor Colour Code

  • The code is a convenient way to tell the resistance of a resistor.
  •  It is also used for other components such as capacitors
  •  Coloured bands are placed on a resistor.  Each band has a numerical value.
  •  Bands are read from left to right.
    
1 - First colour band = 1st digit
2 - Second colour Band = 2nd digit        
3 - Third colour Band  = Multiplier
The last band (usually separated from the others) = the tolerance (how accurate the R value is)
 
 Resistors colour codes - The following table should be memorized
 
COLOUR OF BAND
FIRST BAND
SECOND BAND
Multiplier
Tolerance
BLACK
0
0
1
 
BROWN
1
1
10
 
RED
2
2
 
100
 
ORANGE
3
3
1,000
 
YELLOW
4
4
10,000
 
GREEN
5
5
100,000
 
BLUE
6
6
1,000,000
 
VIOLET
7
7
10,000,000
 
GRAY
8
8
100,000,000
 
WHITE
9
9
1,000,000,000
 
SILVER
 
 
 
+ or - 10%
GOLD
 
 
 
+ or - 5%
 
EXAMPLE:  What is the value of resistance of a resistor with the following coloured bands:

Yellow, green, red, gold
Solution
Yellow = 4   à  first number = 4
Green  = 5   à    second number = 5
Red (in the third band) = X100
Therefore: THE VALUE OF THE RESISTOR IS 45x100 = 4,500 ohms   OR 4.5kΩ (4.5 KILO-OHMS)
 
Since the last band is gold, the accuracy of this resistor is ± 5%.  
This means that it can have a value that can go from a high value of  [4500 + 5%*(4500)] = [4500 + 225] = 4725 Ω to a low value of  .....     [4500 – 5%*(4500) ] = [4500  - 225] = 4275 Ω