Resistor colour codes can sometimes be a little confusing until you understand how they work. But once you get the hang of them it becomes easier to read the values of those simple colour coded bands.
There is a lot of information both online and on this Electronics Tutorials website too, to help you read and understand how resistor colour codes work and this free, simple to use and practical resistor colour code wheel will hopefully help you on your way.
Generally, resistors are too small in size for manufacturers to print numbers and letters on them to indicate their resistive value and tolerance. Luckily for us, some bright spark somewhere invented a resistor colour coding system to make our lives easier and help us to work it out with our free resistor colour code wheel. Fixed resistors have different coloured rings or bands around them to indicate their resistive value with each coloured band having a decimal value associated with it.
Our Resistor Colour Code Wheel
There are many clear advantages to using a colour coding system on electrical and electronic components. The main advantage of using coloured rings or bands around a resistors body, is that they can be very easily seen and read no matter what the position or orientation of the resistor on a board. These coloured bands can also be read even if the resistors body is a little dirty or badly burnt.
We saw in our Ohm’s Law tutorial that resistors are used to limit the amount of current flowing in a circuit so it is important to know their resistive value and depending upon the type, size and tolerance of the resistor, there can be three, four or five coloured bands used to do this.
Although these coloured bands represent nominal or ideal values, they are a good approximation of the actual resistance value. This is because the actual resistive value can have a percentage variation of resistance either side of the nominal value. This variation is called the “tolerance”.
All fixed resistors have a tolerance ranging from less than a tenth of a percent, (0.1%) up to 20% for large carbon types. So a tolerance of 5, 10 and 20 percent, means that the actual value of the resistor can vary from the expected nominal value by as much as ±5, ±10, and ±20%. For example, a 100Ω resistor with a tolerance of ±10% can have a value from 90Ω (-10%) to 110Ω; (+10%). That’s a variation of 20Ω and still be in tolerance.
Resistors with just three coloured bands generally have no (none) tolerance band as they have a fixed tolerance of ±20%. The first two coloured bands are the digit or number bands and the third is known as the multiplier. When there are four bands, the first two coloured bands are the digit bands, the third is the “multiplier”, with the fourth band being the “tolerance” value. On resistors with five coloured bands, the first three colours are always digit bands followed by the multiplier and tolerance bands.
Step 1 – Download and Print
Using our simple and free resistor colour code wheel we can now make sense of all these different coloured bands and what they mean. But first things first. We need to download and print out the Resistor Colour Code Wheel template using the download button below. Its completely free!
Note that this is a PDF (Acrobat) Document File. Please make sure that you have an application to open this file type before downloading the resistor colour code wheel template.
After you have download and printed out the resistor colour code wheel template, you should have an A4 sized paper (or whatever size you want to print out) colour wheel template looking like this:
The Resistor Colour Wheel Template
Note that you can print this resistor colour code wheel template onto any size or density (weight) of paper that you want. It all depends upon your printer and what you have. The standard A4 sized printer or office copier paper has a paper density or weight of 80 g/m2. This standard printer paper is fine and can be used to make the resistor colour wheel.
However, being thin printing paper it can easily be torn or damaged with use, so a paper density of 150g/m2 or more such as thin card would be a better choice and more durable. It would also be possible to laminate the template sheet after printing to both strengthen and prolong its life, the choice is yours. Anyway once you have the resistor colour code wheel template downloaded to your hard drive, you can print it out as many times as you want.
Step 2 – Cut Out the Discs
Having printed out our resistor colour code wheel template from the link above on to suitable paper, we now need to carefully cut out the five coloured discs as shown using scissors or a sharp knife.
Once we have our five coloured discs cut out we can now start to assemble them together to form the finished colour wheel design.
Step 3 – Assemble the Discs
In order to assemble our five individual coloured discs together to create the finished resistor colour code wheel, we need to use a brass paper fastener like the ones shown or something similar that you may have easily available.
Carefully poke or make a hole through the center of each wheel using a pin, needle, compass point, knife or any other sharp object you have, being careful not to cut yourself in the process. The hole you make needs to be the same diameter as the brass paper fasteners. Make sure that the hole you make is big enough to both insert and rotate the paper fastener, or whatever you decide to use. In my case the hole was about 4mm (5/32″) in diameter.
Insert the paper fastener through each hole in turn, starting with the smallest disc and working upwards making sure that each disc is free to rotate as you assemble. Once complete bend the fasteners tabs over at the back of the larger disc. You should now have an assembled resistor colour code wheel that looks something like this.
Assembled Resistor Colour Code Wheel
Step 4 – Using the Colour Wheel
Now that we have assembled our resistor colour code wheel its time to start using it. In the following examples we are going to use it to find the values of a 4-band and a 5-band resistor. But first we will define what each coloured disc is in relationship to the meaning of the coloured bands on a resistors body.
- Disc One (1st Digit) – This is for the first coloured band closest to the end of the resistor on the left hand side and represents the first digit of the resistors value.
- Disc Two (2nd Digit) – This is for the second coloured band along representing the second digit of the resistors value.
- Disc Three (3rd Digit) – This is used for metal film resistors which use a five and six-band colour code for more precise values. In this case the first three coloured bands indicate the first three numerical digits. For a three or four band colour coded resistor this 3rd digit can be ignored.
- Disc Four (the multiplier) – The next coloured band is the mathematical multiplier which represents the number of zeros to be added to the first two (or three) digits. If the third colour, for a 4-band resistor or the fourth colour, for a 5-band resistor, is either gold or silver, this represents a fractional decimal multiplier as the resistive value is less than 10Ω. If the coloured band is Gold, multiply the first two or three digits by 0.1 (divide-by 10) and if the coloured band is Silver multiply by 0.01 (divide-by 100).
- Disc Five (the tolerance) – The final coloured band represents the tolerance of the resistor. A Gold band indicates a tolerance of ±5% while a Silver band indicates a tolerance of ±10%. If there is no coloured band as in a three band resistor, then the tolerance is ±20%.
Note that a resistor can have 3, 4 or 5 coloured bands to indicate its resistive value. The coloured bands that are grouped, or closer together on one side of the resistors body indicate the resistive value of the resistor and you should start here reading from left to right. A single coloured band separate from the group and on its own will be the tolerance value.
In this first example, we are going to use the resistor colour code wheel we have just made to find the resistive value of the following 4-band resistor which is used for most resistors.
4-band Resistor Colour Code
The coloured bands are shown as: YELLOW , VIOLET, ORANGE and GOLD. Then the resistance using the colour wheel is found as:
As this is a 4-band resistor and the resistor colour code wheel can be used to find the resistive values of 5-band resistors, then the 3rd digit wheel is not used in this case. Then the colour code wheel shows:
The first colour band (Yellow) gives the first digit value of 4. The second colour band (Violet) gives the second digit value of 7. This gives a two digit value of 47. Multiply this by the value of the third band. In this case, Orange which has a value of 1000 or 1k, so the resistor has a resistive value of 47,000 ohms (47 × 1000 = 47000) or 47kΩ. The last band gives the resistors tolerance value and Gold equals a tolerance range of ±5%.
Then using the resistor colour wheel, the resistor has the following resistance:
Yellow Violet Orange = 4 7 3 = 4 7 x 103 = 47000Ω or 47kΩ ±5%.
In this second example, we will use it to find the value of the following 5-band resistor. Five band colour codes are used to provide more precise values in precision metal-film resistors with lower tolerances.
5-band Resistor Colour Code
The coloured bands are shown as: BLUE, RED, BLACK, BROWN and BROWN. Then the resistance using the colour wheel is found as:
As this is a 5-band resistor, all the discs of the resistor colour code wheel can be used to find the resistive value. Then the colour code wheel shows:
The first colour band (Blue) gives the first digit value of 6. The second colour band (Red) gives the second digit value of 2. The third colour band (Black) gives the third digit value of 0. This gives a three digit value of 620. We now multiply this by the value of the fourth band, Brown which has a value of 10. So the resistor has a resistive value of 6200 ohms (620 × 10 = 6200) or 6k2Ω. The last band gives the resistors tolerance value and Brown equals a tolerance range of ±1%.
Then using the resistor colour wheel, the resistor has the following resistance:
Blue Red Black Brown = 6 2 0 0 = 6 2 0 x 10 = 6200Ω or 6k2Ω ±1%.
So there you have it, a fun little project to do at home for use at school or the science lab, just download, print and cut out to give you a very useful reference tool for finding the resistive values of 4 or 5-band resistors using this free and simple Resistor Colour Code Wheel.
This resistor colour code wheel is simple to use, just position the colours of the discs and read off the number its that easy and simple, and for checking the value of more resistors, just rotate the coloured discs and you will get another colour scheme. But remember, if you are still unsure of a resistors value, you can always find its resistance using a multimeter or check out our Resistor Colour Codes tutorial.