A worked example
A resistor with bands Brown–Black–Red–Gold is a 1kΩ ±5% resistor — Brown=1, Black=0, Red=×100 multiplier, Gold=±5% tolerance.
Frequently asked questions
Why do resistors use color bands instead of printed numbers?
The color band system was introduced because tiny resistors are too small for readable printed numbers at many sizes, and the colored rings are easy to read under magnification from any angle, regardless of how the component is oriented on a board.
What's the difference between a 4-band and 5-band resistor?
A 4-band resistor uses two digit bands, one multiplier, and one tolerance band. A 5-band adds a third digit for higher precision — common in precision resistors with 1% or 2% tolerance that need more significant figures to express their value accurately.
Why does band 1 not include black?
Black represents zero — a leading zero in a resistance value makes no sense (0.1kΩ would just be written as 100Ω), so manufacturers don't use black for the first significant digit band.