Resistor Color Coding

All resistors have a color code on them, this is a quick little guide to help you along with the process. Below is the chart of the color codes and what they mean.

The value:

Now, how to read this chart; Below is an image of a resistor.

We see there are 4 strips. The first 3 are the value of the resistor, and the last is the tollerance. The first stripe is brown, so we look for brown on the chart. When brown is the first or second digit, it = 1. The next stripe is black. When black is the first or second digit, it = 0. So now we have 10. The third stripe is gold which means we multiply the value from the first two digits by 0.1. This gives us 1. So this is a 1 ohm resistor.

Here is another resistor

The first stripe is violet - 7. The second stripe is red - 2 so 72. The third stripe is x1,000 so 72 * 1000 = 72,000. This is a 72,000 ohm resistor.

Last one, then I'll talk about the last stripe and give you some tips and tricks.

In case you can't see the stripes, it goes Yellow - Violet - Brown. If you don't trust me, click the picture to see it in a higher resolution. The first stripe is yellow, so 4. The second stripe is violet (purple) so that means 7. The last stripe is brown so the multiplier is 10. 47 * 10 = 470. This is a 470 ohm resistor.

The Tollerance:

Alright, by now you're probably thinking to yourself "Alright, I've got the color coding down, what the hell does that last stripe mean?". And if you weren't thinking that, then you were thinking "I wasn't thinking that" the whole time you were reading the last sentence. The last stripe is the tollerance. The tollerance is how much the resistor can be varried, and the standard is usually 5%. For a 100 ohm resistor with 5% tollerance, the resistor can have an actual value between 95 and 105 ohms. To figure this out, you'll need some very basic math skills

5% as a decimal is 0.05 - Multiply the resistor value by the tollerance (as a decimal) to get the variance. So 100*0.05 = 5. The variance is how much the resistor can vary either way so on a 100 ohm resistor, it can vary + or - 5 so 105 or 95. Here are the above resistors, with the tollerance added and final actual value range.

A shorthand method (if you will) is to multiply the resistors value by the tollerance's inverse decimal to get the minimum. Now, before you have a brain fart, I'll explain that to you. If the tollerance is 5% (0.05) then the exact opposite (inverse) is 95% (0.95). Multiplying any resistor value by it's tollerance inverse will always give you its minimum value. - - To find the maximum value you just add 1 to the tollerance as a decimal. So 0.05 becomes 1.05. Multiplying any resistor value by it's tollerance decimal + 1 will always give you it's maximum value.

Last stripe is gold, so 5% tollerance. 1* 0.95 = 0.95 (minimum value) 1* 1.05 = 1.05 (maximum value)

Next one

Tollerance again is 5%. 72000 * 0.95 = 68,400 (minimum value). 72000 * 1.05 = 75,600 (maximum value)

Last one, then on to tips and tricks

This one also has a tollerance of 5%. 470 * 0.95 = 465.5 (minimum value). 470 * 1.05 = 493.5 (maximum value)

So you can see that as the resistance goes up, the range gets bigger. However normally any circuit that requires a bigger resistor can handle a bigger variance. If it can't, thats where 1% tollerance resistors come in.

Some Tips to help you in your color coding adventures:

• Remembering the color chart is always a big step. You can start yourself by remembering that the chart goes Black, Brown, ROYGBV, Grey, White. For those who don't know what ROYGBV is, Click the link.
• When trying to figure out which way to read the resistor (you have to read the stripes in the correct order) just remember that the first stripe will never be a gold or silver stripe.
• Get quick at math, if you're not already. It's always fun to have someone point at a resistor and be able to tell them what it is within a second or two.
• Shorthand is your friend!