# Resistor Color Codes

The electronic colour code for resistors was developed in the early 1920s, and allows coding on physically small components where printed text is difficult or impossible. Coloured markings are easier to read in 360 degrees without magnification, more resistant to abrasion, and still readable when chipped or partly obscured.

The idea is that coloured bands of different colours are painted on the resistor body, with each colour corresponding to a number. Tolerances are aslo colour coded. The first band is always closer to one end of the body, and the resistor value and tolerance are read from the bands. This system of colour markings is very common and in widespread use world wide.

 Band A:- 1st significant digit (closest to the end) Band B:- 2nd significant digit Band C:- Multiplier (10^x) Band D:- Tolerance (spaced further from the other bands) for example, a resistor with 4 bands coloured:- brown, red, green, gold = 1st digit-1, 2nd digit-2, Multiplier-5 (=10^5 =100,000), tol-gold = 1.2 MOhms 5%

See table below for values:-

 Band values Tolerance values No. Colour Multiplier Tol. Colour 0 Black x100 (1) 1 Brown x101 (10) ±1% Brown 2 Red x102 (100) ±2% Red 3 Orange x103 (1,000) 4 Yellow x104 (10,000) 5 Green x105 (100,000) 6 Blue x106 (1,000,000) 7 Violet x107 (10,000,000) 8 Grey x108 (100,000,000) 9 White x109 Gold x10-1 (0.1) ±5% Gold Silver x10-2 (0.01) ±10% Silver ±20% None

A mnemonic for helping to remember these colours is:-
"Bad Boys Ravish Only Young Girls But Violet Gives Willingly"

The standard 20% resistor values (E6) for one decade values are as follows:-
10, 15, 22, 33, 47, 68

The standard 10% resistor values (E12) for one decade values are as follows:-
10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82

The standard 5% resistor values (E24) for one decade values are as follows:-
10, 11, 12, 13, 15, 16, 18, 20, 22, 24, 27, 30, 33, 36, 39, 43, 47, 51, 56, 62, 68, 75, 82, 91

Resistors have no polarity and can be connected either way.