Resistors will have either 3 or 4
bands on them. The first three bands tell you how to compute the
resistance in
ohms. The fourth, if present, indicates the
tolerance (
accuracy).
Color Band 1 Band 2 Band 3
gold X X x .01
silver X X x .1
Black 0 0 x 1
Brown 1 1 x 10
red 2 2 x 100
orange 3 3 x 1,000
yellow 4 4 x 10,000
green 5 5 x 100,000
blue 6 6 x 1,000,000
violet 7 7 x 10,000,000
gray 8 8 x 100,000,000
white 9 9 x ---------
Band four(
tolerance band code):
Gold = ±5%
Silver = ±10%
None = ±20%
Red = ±2%
Brown = ±1%
EXAMPLE
You have a
resistor with bands: brown-black-red, what is it's
resistance in
ohms?
band one(brown) = 1
band two(
black) = 0
band
three(red) = 100
(band 1 & 2) * (band 3) = resistance
10 * 100 = 1000 or 1K
Therefor a
resistor with bands brown-black-red would be a 1K
ohm resistor. Since the
fourth band is not present, it has a ±20%
accuracy.