Introduction

A resistor is a perhaps the most common building block used in circuits. Resistors come in many shapes and sizes this tool is used to decode information for color banded axial lead resistors.

4 Band Description

The number of bands is important because the decoding changes based upon the number of color bands. There are three common types: 4 band, 5 band, and 6 band resistors. For the 4 band resistor:

Band 1 – First significant digit.

Band 2 – Second significant digit

Band 3 – Multiplier

Band 4 – Tolerance

Resistance Value

The first 4 bands make up the resistance nominal value. The first 2 bands make up the significant digits where:

black – 0

brown – 1

red – 2

orange – 3

yellow – 4

green – 5

blue – 6

violet – 7

grey – 8

white – 9

The 3rd band or multiplier band is color coded as follows:

black – x1

brown – x10

red – x100

orange – x1K

yellow – x10K

green – x100K

blue – x1M

violet – x10M

grey – x100M

white – x1G

gold – .1

silver – .01

An example of a resistance value is:

band 1 = orange = 3,

band 2 = yellow = 4,

band 3 = blue = 1M

value = 34*1M = 34 Mohm

Resistance Tolerance

The fourth band is the tolerance and represents the worst case variation one might expect from the nominal value. The color code for tolerance is as follows:

brown – 1% 

red – 2% 

orange – 3% 

yellow – 4% 

green – .5% 

blue – .25% 

violet – .1% 

gray – .05% 

gold – 5% 

silver – 10%

An example calculating the range of a resistor value is:

If the nominal value was 34 Ohm and the 4th band of the resistor was gold (5%) the value range would be nominal +/- 5% = 32.3 to 35.7

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