How to Read the Resistor Code

Shawn Hymel
A free video tutorial from Shawn Hymel
Engineering Superhero
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06:47:50 of on-demand video • Updated January 2021

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English [Auto] See when you start making circuits with more than one resistor it can become hard to tell them apart. Luckily the larger through hole resistors have color bands that tell you their resistance you just need to learn how to read the code first determine how many color bands are on your resistor. You will most often find resistors with four bands but ones with three five and six bands exist because four band resistors are the most popular. I'll show you how to read those. You then need to figure out which band is the first band on most resistors. There will be a slightly larger gap between the last and second to last band with the first band on the left. Find the number that corresponds to the color from the chart on this resistor. The first band is yellow So the first numbers 4 then repeat the process for the second band. Violet is the color for number 7. So write that down as the second digit the second to last band is the multiplier and it tells you how many zeros to add to your number. Orange corresponds to the number 3 so we add three zeros that gives us 47 times 1000 which is forty seven thousand ohms or 47 K ohms. The final band is the tolerance gold the most common tolerance band you'll see on inexpensive resistors means 5 percent. This is the tolerance of the resistance that the manufacturer guarantees. So 47 K ohms with a 5 percent tolerance means that the resistor can actually be anywhere between 44000 650 ohms and forty nine thousand three hundred fifty ohms. If we were to measure it. If you do run across a 5 band resistor reading it is very similar. The only difference is that you have three digits instead of two before the multiplier. In this example Green is five Brown as 1 and black is zero. That makes 510 before we add two zeros which we got from the red band. This means this is a 51 ohm resistor. The last band tells us that the tolerance is 1 percent as you start to accumulate a nice collection of resistors. It can be handy to memorize the code so that you don't need to look at a chart every time. Several mnemonics exist to help you memorize the code but my favorite is big beautiful roses occupy your garden but violets grow wild. The first letter in each of these words corresponds to the first letter of the color. You'll just have to remember that Black comes before Brown in the list. Also gold and silver aren't in the mnemonic. Since you rarely need them to read the base value. However it's useful to note that you may see them as a multiplier band in which case you actually divide the resistors value by 10 or 100. There are also many calculators available on the internet. Just search for resistor band calculator Digi-Key for example has one where you can select the colors of the bands and it will give you the resistors value. Let's read a real resistors value for practice. Here we see orange orange red gold starting with 0 for big big beautiful roses Occupy Occupy as orange which is three orange again so three three big beautiful roses for red that's too which is our multiplier band. So we add two zeros to thirty three to get 3300 with a gold tolerance band. That gives us 3.3 Kila ohms plus or minus 5 percent. Knowing how to read resistor codes can be very handy when building or dismantling circuits. If you're having trouble memorizing the code don't worry. Online calculators and charts can help.