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Resistor Codes
Resistor Colour Codes

Note If there is only 3 colour bands, the missing one will be band d.
The absence of band d implies the resistor accuracy is ±20%
 
To read the code,
1. Write down the digit provided by the colour of band a
2. Write down the digit provided by the colour of band b
3. Write down the multiplier provided by the colour of band c
4. You have found the resistance in Ohms
5. If band d is present, this indicates the accuracy of the component.
abcd
black 0 black 0 black x100Ω
brown 1 brown 1 brown x101Ω brown ±1%
red 2 red 2 red x102Ω red ±2%
orange 3 orange 3 orange x103Ω
yellow 4 yellow 4 yellow x104Ω gold ±5%
green 5 green 5 green x105Ω
blue 6 blue 6 blue x106Ω
violet 7 violet 7 violet x107Ω
grey 8 grey 8 grey x108Ω silver ±10%
white 9 white 9 white x109Ω
 
Three Digit Resistor Number Codes

1. Write down the first 2 digits (shown as a on the diagram)
2. Write down "x10"
3. Write down the x10 multiplier given by the third digit
4. This is the resistance in Ohms
 
Here are some examples
234 = 23 x104Ω = 230kΩ
170 = 17 x100Ω = 17Ω
135 = 13 x105Ω = 1.3MΩ
 
Number and One Letter Resistor Codes

1. Write down all digits before the letter. (If there are no digits before the letter then write "0")
2. Write down a decimal point "."
3. Write down all the digits after the letter
4. Look the letter up in this table and write down the answer
LetterAnswer
RΩ
kkΩ
MMΩ
GGΩ
Here are some examples
23M45 = 23 . 45 M Ω = 23.45MΩ
470k = 470 . 0 k Ω = 470kΩ
1R2 = 1Ω2 = 1.2Ω
1k = 1kΩ
12G0 = 12.0GΩ
G47 = 0.47GΩ = 470MΩ
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