This document discusses the resistor color code used to identify resistor values. It explains that the first three color bands represent the resistance value in ohms and the tolerance. Common resistor values are part of the E12 series. The document provides tables to practice determining resistor values from color codes and measuring actual resistor values with a multimeter. Questions at the end assess understanding of tolerances and variations in measured values.
The electronic color code is used to indicate the values or ratings of electronic components, usually for
resistors, but also for capacitors, inductors, and others. A separate code, the 25-pair color code, is used
to identify wires in some telecommunications cables.
The electronic color code was developed in the early 1920s by the Radio Manufacturers Association
(now part of Electronic Industries Alliance(EIA)), and was published as EIA-RS-279. The current
international standard is IEC 60062.published by International Electrotechnical Commission.
Colorbands were used because they were easily and cheaply printed on tiny components. However,
there were drawbacks, especially for color blind people. Overheating of a component or dirt
accumulation, may make it impossible to distinguish brown from red or orange. Advances in printing
technology have now made printed numbers practical on small components. Where passive
components come in surface mount packages, their values are identified with printed alphanumeric
codes instead of a color code.
The resistance value, tolerance, and wattage rating are generally printed onto the body of the resistor
as numbers or letters when the resistors body is big enough to read the print, such as large power
resistors. But when the resistor is small such as a 1/4W carbon or film type, these specifications must
be shown in some other manner as the print would be too small to read.
So to overcome this, small resistors use coloured painted bands to indicate both their resistive value
and their tolerance with the physical size of the resistor indicating its wattage rating. These coloured
painted bands produce a system of identification generally known as a Resistors Colour Code.
An international and universally accepted Resistor Colour Code Scheme was developed many years
ago as a simple and quick way of identifying a resistors ohmic value no matter what its size or condition.
It consists of a set of individual coloured rings or bands in spectral order representing each digit of the
resistors value.
The resistor colour code markings are always read one band at a time starting from the left to the right,
with the larger width tolerance band oriented to the right side indicating its tolerance. By matching the
colour of the first band with its associated number in the digit column of the colour chart below the first
digit is identified and this represents the first digit of the resistance value.
1. 1
Laboratory manual series for basic Electrical
Engineering
Getting Started – Resistor Colour Code
By Isuru Premaratne
Version: 2016 January
Getting Started – Resistor Colour Code by Isuru Premaratne is licensed under a Creative Commons
Attribution-NonCommercial-ShareAlike 4.0 International License.
Based on a work by James M. Fiore at http://www.dissidents.com/books.htm.
For more information or feedback, contact:
Isuru Premaratne
isuru109@outlook.com
2. 2
Resistor Colour Code
Objective
The objective of this exercise is to learn the resistor colour code. The second objective is to become
familiar with the measurement of resistance using a digital Multimeter (DMM).
Theory Overview
The resistor is perhaps the most fundamental of all electrical devices. Its fundamental attribute is the
restriction of electrical current flow: The greater the resistance, the greater the restriction of current.
Resistance is measured in Ohms. The measurement of resistance in unpowered circuits may be
performed with a digital Multimeter. Like all components, resistors cannot be manufactured to
perfection. That is, there will always be some variance of the true value of the component when
compared to its nameplate or nominal value. For precision resistors, typically 1% tolerance or better,
the nominal value is usually printed directly on the component. Normally, general purpose
components, i.e. those worse than 1%, usually use a colour code to indicate their value.
The resistor colour code typically uses 4 colour bands. The first two bands indicate the first two digits
of the resistance value while the third band indicates the power of ten applied (i.e. the number of
zeroes to add). The fourth band indicates the tolerance. It is possible to find resistors with five or six
bands but they will not be examined in this exercise. Usually final colour band indicates the tolerance
and the one before the last indicates the power of ten applied. All colour bands before these two will
indicate the first digits of the resistance value. Also the gap between final band and the adjacent band
will be significantly larger than the remaining gaps. Therefore the order of bands can be identified.
Examples for 4 colour band resistors are shown below:
It is important to note that the physical size of the resistor indicates its power dissipation rating.
3. 3
Each colour in the code represents a numeral. It starts with black and finishes with white, going
through the rainbow in between.
Colour Value
Multiplier (power
of ten)
Black 0 100
= 1
Brown 1 101
= 10
Red 2 102
= 100
Orange 3 103
= 1k
Yellow 4 104
= 10k
Green 5 105
= 100k
Blue 6 106
= 1M
Violet 7 107
= 10M
Grey 8 108
= 100M
White 9 109
= 1G
Gold ±5 % 10-1
= 0.1
Silver ±10 % 10-2
= 0.01
No
colour
±20 %
For example, a resistor with the colour code brown-red-orange-silver would correspond to 1 2
followed by 3 zeroes, or 12,000 Ohms (more conveniently, 12 k Ohms). It would have a tolerance of
10% of 12 k Ohms or 1200 Ohms. This means that the actual value of any particular resistor with this
code could be anywhere between 12,000-1200=10,800, to 12,000+1200=13,200. That is, 10.8 k to
13.2 k Ohms. Note, the IEC standard replaces the decimal point with the engineering prefix, thus 1.2
k is alternately written 1k2.
Similarly, a 470 k 5% resistor would have the colour code yellow-violet-yellow-gold. To help
remember the colour code many mnemonics have been created using the first letter of the colours to
1st band
1st digit
2nd band
2nd digit
3rd band
Power of ten
4th band
Tolerance
Gap to identify the
tolerance band
4. 4
create a sentence. One example is the picnic mnemonic Black Bears Robbed Our Yummy Goodies
Beating Various Gray Wolves. You can create your own mnemonics.
Resistors come to the market as a series of values. This means we cannot obtain every resistance
value but have to search for available values. The most common series of resistors is E12. Following
table shows the available values in E12 series.
1.0 1.2 1.5 1.8 2.2 2.7 3.3 3.9 4.7 5.6 6.8 8.2
10 12 15 18 22 27 33 39 47 56 68 82
100 120 150 180 220 270 330 390 470 560 680 820
All these values are available in multiples of powers of ten. Therefore the next set of values is 1k,
1.2k, 1.5k, ……., 8.2k. If you look at the values carefully, you will realize that only 12 different
combinations are available for the first two digits of this E12 series. Third colour band is always the
multiplier. When you start to read resistor values practically you will become more familiar with these
E12 resistor values and thereafter reading will be very easy.
Measurement of resistors with a DMM is a very straight forward process. Simply set the DMM to the
resistance function and choose the first scale that is higher than the expected value. Clip the leads to
the resistor and record the resulting value.
Equipment
Digital Multimeter model: ________________
Procedure
1. Given the nominal values and tolerances in Table 3.1, determine and record the corresponding
colour code bands.
2. Given the colour codes in Table 3.2, determine and record the nominal value, tolerance and
the minimum and maximum acceptable values.
3. Obtain a resistor equal to the first value listed in Table 3.3. Determine the minimum and
maximum acceptable values based on the nominal value and tolerance. Record these values in
Table 3.3. Using the DMM, measured the actual value of the resistor and record it in Table
3.3. Determine the deviation percentage of this component and record it in Table 3.3. The
deviation percentage may be found via:
𝐷𝑒𝑣𝑖𝑎𝑡𝑖𝑜𝑛 = 100 ×
𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑑 − 𝑛𝑜𝑚𝑖𝑛𝑎𝑙
𝑛𝑜𝑚𝑖𝑛𝑎𝑙
Circle the deviation if the resistor is out of tolerance.
4. Repeat Step 3 for the remaining resistors in Table 3.3.
5. 5
Data Tables
Table 3.1
Value Band 1 Band 2 Band 3 Band 4
27 @ 10%
56 @ 10%
180 @ 5%
390 @ 10%
680 @ 5%
1.5 k @ 20%
3.6 k @ 10%
7.5 k @ 5%
10 k @ 5%
47 k @ 10%
820 k @ 10%
2.2 M @ 20 %
Table 3.2
Colours Nominal Tolerance Minimum Maximum
red-red-black-silver
blue-gray-black-gold
brown-green-brown-gold
orange-orange-brown-silver
green-blue-brown –gold
brown-red-red–silver
red-violet-red–silver
gray-red-red–gold
6. 6
brown-black-orange–gold
orange-orange-orange–silver
blue-gray-yellow–none
green-blue-green-silver
Table 3.3
Value Minimum Maximum Measured Deviation
10 @ 10%
100 @ 5%
150 @ 5%
330 @ 10%
560 @ 5%
1.2 k @ 5%
2.7 k @ 10%
8.2 k @ 5%
10 k @ 5%
33 k @ 10%
100 k @ 10%
1 M @ 20 %
Questions
1. What is the largest deviation in Table 3.3? Would it ever be possible to find a value that is
outside the stated tolerance? Why or why not?
2. If Steps 3 and 4 were to be repeated with another batch of resistors, would the final two
columns be identical to the original Table 3.3? Why or why not?
3. Do the measured values of Table 3.3 represent the exact values of the resistors tested? Why or
why not?