As shown above, a carbon-composition resistor can have 4 to 6 bands. A 5-band resistor is more precise compared to a 4-band type because of the inclusion of a third signficant digit. A 6-band resistor is like a 5-band resistor but includes a temperature coefficient band (the 6th band).

  4-band 5-band 6-band
1st band 1st significant digit 1st significant digit 1st significant digit
2nd band 2nd significant digit 2nd significant digit 2nd significant digit
3rd band multiplier 3rd significant digit

3rd significant digit

4th band tolerance multiplier multiplier
5th band N/A tolerance tolerance
6th band N/A N/A temperature coefficient

Each color represents a number if it's located from the 1st to 2nd band for a 4-band type or 1st to 3rd band for a 5-band and 6-band type. 

Color Value

Black (2nd and 3rd bands only)

0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Grey 8
White 9

If the color is found on the 3rd band for a 4-band type or the 4th band for a 5-band and 6-band type, then it's a multiplier.

Color Value

Black

x1
Brown x10
Red x100
Orange x1000
Yellow x10000
Green x100000
Blue x1000000
Violet x10000000
Grey x100000000
White x1000000000

Notice that the number of zeroes is equal to the color's number as per the previous table.

The fourth band (or 5th for the 5-band and 6-band) indicates the tolerance values. Here, two colors are added (gold and silver).

Color Value

Black

N/A

Brown ±1%
Red ±2%
Orange ±3%
Yellow ±4%
Green ±0.5%
Blue ±0.25%
Violet ±0.15%
Grey ±0.05%
White N/A
Gold ±5%
Silver ±10%

The 6th band for a 6-band type resistor is the temperature coefficient. This indicates how much the actual resistance value of the resistor changes when the temperature changes.

Color Value

Black

N/A
Brown 100 ppm/ºC
Red 50 ppm/ºC
Orange 15 ppm/ºC
Yellow 25 ppm/ºC
Green N/A
Blue 10 ppm/ºC
Violet 5 ppm/ºC
Grey N/A
White N/A