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
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 KILOOHMS)
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 KILOOHMS)
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