Resistor Colour Coding - tutorial

You knew that resistors have many colorful lines on their body. these colored lines are known as color bands. resistors are the passive components which are very small in size so it's not easy to print values on the resistors. therefore, color bands are used to print the values indirectly on the resistor.
 this standard was found by the Radio Manufacturers Association(RMA) which is now a part of Electronic Industries Alliance(EIA).

Resistor Colour Bands-

 Above figure shows the color bands available on the resistor, there are four bands A, B, C, and D respectively.

• Band A is the first digit of resistance value
• Band B is the second digit of resistance value 
• Band C is the decimal Multiplier
• Band D is the tolerance band.

Ring color			Significant figures	Multiplier		Tolerance		Temperature coefficient
Name	Code	RAL				Percent	Letter	ppm/K	Letter
None	–	–	–	–		±20%	M	–
Pink	PK	3015	–	×10−3	×0.001	–		–
Silver	SR	–	–	×10−2	×0.01	±10%	K	–
Gold	GD	–	–	×10−1	×0.1	±5%	J	–
Black	BK	9005	0	×100	×1	–		250	U
Brown	BN	8003	1	×101	×10	±1%	F	100	S
Red	RD	3000	2	×102	×100	±2%	G	50	R
Orange	OG	2003	3	×103	×1000	–		15	P
Yellow	YE	1021	4	×104	×10000	±5%	–	25	Q
Green	GN	6018	5	×105	×100000	±0.5%	D	20	Z
Blue	BU	5015	6	×106	×1000000	±0.25%	C	10	Z
Violet	VT	4005	7	×107	×10000000	±0.1%	B	5	M
Gray	GY	7000	8	×108	×100000000	±0.05% ±10%	A	1	K
White	WH	1013	9	×109	×1000000000	–		–

The above table shows the colors of the bands and their respective values for different bands. from these values, we can find the value of any resistor with the color bands present on the body of the resistor.

Finding the final value of resistor -(for resistor having 4 bands)

Now we have everything needed to find the value of resistor so let's see how to find final value 

Let's take an example, we have a resistor with four bands with colors brown, orange, red, gold respectively.

Step 1 - 

band A - Brown - brown has value 1 so the first digit is 1.

Step 2 -

band B - Orange - Orange has value 3, so the second digit is 3.

Step 3 - 

band C - Red - Red has value 2, band c is the multiplier band having the value 10^2 which is 100, therefore now resistance value becomes 13*100=1300 ohms.

Step 4 - 

Band D - Gold - Band D is the tolerance band here gold color shows the + or - 5% tolerance.

Step 5 -

Put all together
First digit-1
Second digit-3
Multiplier-100
Tolerance- + or - 5%

Final value of resistance = 1300 ohms + or - 5%
i.e. Resistance values can vary from 1235 ohms to 1365 ohms.
 Here 5% tolerance means resistance value may differ by + or - 5%.

Resistors Can Have more than 4 bands the number of bands varies from 4-6 bands, according to these bands resistance value can be calculated, refer to the following table.

	4-band	5-band	6-band
1st band	1st significant digit	1st significant digit	1st significant digit
2nd band	2nd significant digit	2nd significant digit	2nd significant digit
3rd band	multiplier	3rd significant digit	3rd significant digit
4th band	tolerance	multiplier	multiplier
5th band	N/A	tolerance	tolerance
6th band	N/A	N/A	temperature coefficient

Important Links-
1.Online resistance color code calculator- AllAboutCircuits
2.Electronic Colour Code- WIKIPEDIA