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Resistor Colour Code Calculator
Resistors are measured in ohms Ω.
Colour "bands" are used to specify each value.
There are three bands, and sometimes four.
The First Two Bands represent the first and second numbers.
The Third Band is the multiplier.
(the number of zeros we place after the first two numbers).
The Fourth Band is the tolerance (allowable deviation above or below the stated value).
There are typically two colours here: Silver (±10%) and Gold (±5%).
If there is no fourth band, the resistor has a ±20% tolerance.
Note:
The colour bands do not represent Scientific Notation or Engineering Notation.
However, the written equivalent is expressed in Engineering Notation using metric prefixes.
The first three bands are coloured:
Black = 0,
Brown = 1,
Red = 2,
Orange = 3,
Yellow = 4,
Green = 5,
Blue = 6,
Violet = 7,
Gray = 8,
White = 9,
The fourth band (if any) is coloured:
None = 20%,
Brown = 1%,
Red = 2%,
Orange = 3%,
Yellow = 4%,
Green = 0.5%,
Blue = 0.25%,
Violet = 0.1%,
Gray = 0.05%,
Gold = 5%,
Silver = 10%,
To use this calculator, select the colour for each band from the drop-down menus.
To calculate a new value, select new drop-down colours, and continue...
EXAMPLE:
BROWN, BLACK would be 10, while BLACK, BROWN is 1 (drop the leading zero).
The third band is the multiplier; (the number of zeros we place after the first two numbers).
Black = no zeros, Brown = one zero, Red = two zeros, Orange = three zeros, Yellow = four zeros, Green = five zeros, Blue = six zeros.
Expressed Algebraically:
(The first two numbers are the coefficient, and the third band is the multiplier.)
When the colour of the third band is:
Black Ω=Coefficient*100,
Brown Ω=Coefficient*101,
Red Ω=Coefficient*102,
Orange Ω=Coefficient*103,
Yellow Ω=Coefficient*104,
Green Ω=Coefficient*105,
Blue Ω=Coefficient*106.
EXAMPLE:
Brown, Black, Blue = 10M Ohms.
NOTE:
For values above 9.9 Ohms, Black is not used in the first band.
In the first band, Brown is the first allowable colour for resistors with values of 10 ohms or greater.
EXAMPLE:
Brown, Black, Red = 1000 Ohms.
Do not use Black, Brown, Orange in an attempt to represent 1000 Ohms.
1000 ohoms is greater than ten ohms and must not begin with a zero.
EXAMPLE:
A 1000 Ohm resistor with a 20% tolerance could deviate by ±200Ω.
So the resistance can fall between 800Ω and 1200Ω.
NOTE:
Silver is the most common tolerance band.
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