Resistor colour codes are well worth learning. Once you know them it’s something you will remember. It’s like riding a bike and there are only ten colours to remember.

Once you know the colour bands it a case of where they go on the resistor to work out its value. When you get used to looking at lots of resistors you don’t even work out the values you just recognise the groups of colours and just “know” the value!

4 band resistors used to be the most common types you would see. Almost all resistors had 4 bands when I started to become interested in electronics. The resistor colour code is shown below. The numbers stay the same regardless of whether it's the first, second or third band.

With a 4 band resistor the first stripe of colour is the first digit. The second stripe of colour is the second digit while the third stripe is the multiplier. This always seemed to confuse me until it was pointed out to me that the number is just the number of zeros, so brown means 1 zero and orange is 3 zero’s. The forth stripe is the tolerance.

A 4 band resistor.

looking at the picture above the first band is brown so that's a "1".

The second band is grey so that's an "8".

The third band is yellow so that's 4 zero's.

So putting it together we get 1 8 0000. That's 180,000 ohms, replacing the three 000's with a K as it's usually known as 180K.

The fourth band is gold so that's 5% tolerance.

Going back a few years the tolerance was commonly silver for 10% or gold for 5%, now red and brown for 2% and 1% are more common. The full tolerance colours are shown below.

A resistors tolerance is how close to the value it could be. Resistors are not usually spot on, without wanting to over complicate the three most common colours that you will see are gold, brown and red. Gold means that the tolerance is five per cent. So the value could be wrong by five per cent so a 100 ohm resistor could be as low as 95 ohms or as high as 105 ohms. Brown is for one percent tolerance so a 100 ohm resistor could be as low as 99 ohms as high as 101 ohms and a red tolerance band would mean a tolerance of two per cent so a 100 ohm resistor could be as low as 98 ohms or as high as 102 ohms

Shown below are three very common resistor values.

The first strip is brown, which is 1 so the first digit is 1.

The second stripe is black, which is 0 so the second digit is 0.

The third stripe is red, which is 2 so there are two zero’s.

So putting it together we have a 1 0 00.

That’s 1,000 ohms which is also known a 1 kilo ohm or 1k.

The first strip is brown, which is 1 so the first digit is 1.

The second stripe is black, which is 0 so the second digit is 0.

The third stripe is orange, which is 3 so there are three zero’s.

So putting it together we have a 1 0 000.

That’s 10,000 ohms which is also known a 10 kilo ohm or 10k.

The first strip is brown, which is 1 so the first digit is 1.

The second stripe is black, which is 0 so the second digit is 0.

The third stripe is yellow, which is 4 so there are four zero’s.

So putting it together we have a 1 0 0000.

That’s 100,000 ohms which is also known a 100 kilo ohm or 100k.

Not very common anymore, in fact so uncommon I can’t find one to take a picture of, but you may come across 3 band resistors. The first colour is the first digit the second colour is the second digit and the third is the multiplier. They are basically like the four band resistors but without the four tolerance band. Theses resistors weren’t the most accurate and were manufactured to be around twenty percent tolerance.

5 band resistors are now more popular that the four band types. Five bands is the new four bands. As manufacturing techniques improved and electronics has become more precise, extra values of resistors have appeared between the previous values. You can now get a 287 ohm resistor for instance. Obviously not a value that you could have indicated with the 4 band resistor code and so the five band code was introduced. Don’t worry you don’t have to rip up the old ways and learn something completely different, it’s just that now the third band becomes the third digit and the fourth band the multiplier.

From the above picture you can see that the first band is blue so that's a "6".

The second band is green so that's a "5"

The third band is black so that's a "0".

The fourth band is red so that's two zero's.

Putting that together we get 6 5 0 00 or 65K. The fifth band is brown signifying a 1% tolerance.

I know what you’re thinking, where’s this going to end? Well for the moment this is it, six bands is as far as we go. As for what they all mean don’t worry they are almost like the 5 band variety with an extra band at the end to indicate the temperature coefficient of the resistor. To you and me that’s how much the resistors value will change with temperature change .

39K 1% 50 ppm resistor.

Yellow | White | Black | Red | Brown | Red |
---|---|---|---|---|---|

3 | 9 | 0 | 00 | 1% | 50ppm |

The picture above shows the colours used to indicate the resistor's temperature co-efficient.

You may need to use a magnifier to read the colours on some of the smaller resistors and while your learning you can check the values with a test meter. This is the one that I use you can read more about it here if you're interested. As you may be aware there are set values of resistors you can find out more here.

At some point gold and silver where introduced into the code for the number of zero,s or multiplier band. Gold is 0.1 and silver is 0.01. An easy way to understanding this is if the multiplier band is red the normal colour for 2 then there are two zero's, brown is one zero and black is no zeros. If the multiplier is gold you move the decimal place one place back.

For example a yellow, violet, black would be 47 Ohms.

a yellow, violet, gold would be 4.7 ohms.

Shown below is a handy A4 size PDF for you to down load and print off to keep by your work bench.