Unlike Through hole resisors which use colored bands to determine the value, surface mount resistor have numbers and sometimes letters. I will teach you how to take those letters and digits and determine the value.

Looking at the image you see 4 resistors, the first being 391 the seconed 270 and the two at the bottom are the same 30R9. That does not stand for a 391 ohm , 270 ohm, and so on. The formula for breaking the code down is as follows.

1st value-2nd value-multiplier

3 9 1 = 390 ohm resistor

2 7 0 = 27 ohm resistor

2 3 3 = 23000 ohm or 23K ohm resistor

There are some resistors which have 4 digits. The formula is the same with the addition to a digit.

1st value-2nd value-third value-multiplier

2 3 5 3 = 235K ohm resistor

You may ask"why some have three diigits and some have four?" three digits typically means that the resistor is 5% tolerance the four digit typically means the resistor is 1% tolerance. If a letter is used to represent tolerance use the chart below.

B=.1%

C=.25%

D=.5%

F=1%

G=2%

J=5%

K=10%

M=20%

Z=80%

Now you will notice that the last two resistor have an "R" in the equation. The way to look at these is very simple. The R represents a decimal. So 30R9 is a 30.9Ohm resistor.

R23= .23 ohm

5R6= 5.6 ohm

45R3= 45.3 ohm

Of course you can read the values with a meter, but whats the fun in that? I hope you all learned something from this little write up.

Looking at the image you see 4 resistors, the first being 391 the seconed 270 and the two at the bottom are the same 30R9. That does not stand for a 391 ohm , 270 ohm, and so on. The formula for breaking the code down is as follows.

1st value-2nd value-multiplier

3 9 1 = 390 ohm resistor

2 7 0 = 27 ohm resistor

2 3 3 = 23000 ohm or 23K ohm resistor

There are some resistors which have 4 digits. The formula is the same with the addition to a digit.

1st value-2nd value-third value-multiplier

2 3 5 3 = 235K ohm resistor

You may ask"why some have three diigits and some have four?" three digits typically means that the resistor is 5% tolerance the four digit typically means the resistor is 1% tolerance. If a letter is used to represent tolerance use the chart below.

B=.1%

C=.25%

D=.5%

F=1%

G=2%

J=5%

K=10%

M=20%

Z=80%

Now you will notice that the last two resistor have an "R" in the equation. The way to look at these is very simple. The R represents a decimal. So 30R9 is a 30.9Ohm resistor.

R23= .23 ohm

5R6= 5.6 ohm

45R3= 45.3 ohm

Of course you can read the values with a meter, but whats the fun in that? I hope you all learned something from this little write up.

<p>Excellent explanation of SMD Values. </p><p>As a newbie to SMD I have found myself a little daunted by this miniature hardware, but I am now more confident of installing the correct resistor when constructing my projects.</p><p>Lance</p><p>- I now have a (cheap) bulk lot of mixed SMD on the way to practice my soldering skills -</p>

<p>Hi Instructables, I have looked up many sites to find the best explanation on SMD resistor colour codes. Your one is excellent. I will recommend this explanation to everyone who is searching for a good basic understanding.</p><p>Dave.</p>

<p>Can i use that usual resistor with color coding instead of SMD resistor of same value(ohms) in a project ????</p>

What if you have some without any markings at all? <br>

hi,i am neeraj i m joining a new member in ur electronic world. plz.help me.

Here's the full link. The part after and including the last % is not needed. <br> <br>http://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Data+Sheet%7F1773204%7FH%7Fpdf%7FEnglish%7FENG_DS_1773204_H.pdf <br> <br>Hope this helps.

There is a completely different code used on some resistors. It has to do with a three number scheme that allows 1% values. I found a good reference here: <br> <br>http://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Data+Sheet%7F1773204%7FH%7Fpdf%7FEnglish%7FENG_DS_1773204_H.pdf%7F1622827-1 <br>

I like to put the surface mount resistor on a hard surface then smash it open with a rock. Then like reading tea leaves I divine what it's resistance once was ...

Pfred i gather from this post ,and others, that you aren't a fan om SMD. :0)

Should I be? When I strip boards with SMD on them I just let those parts float on the top of my solder pot until I skim it. So when I say SMT stinks I mean it literally!

!!! "Perfect" !!! <br> <br>Exactly what ive been wanting to know to get into SMD soldering !! <br> <br>Thanks a bunch for taking the time to make this nice and simple 'ible so a complete beginner (started this year!) in electronics can easily digest ! <br> <br>Keep up the GREAT work and hopefully some more write-ups on SMD's ! <br> <br>Oh by the way, how would i measure the capacitance of a SMD capacitor using a DMM ?? <br>many thanks in advance fo a noob question but my friend google hasnt turned up much, or maybe im not searching for the right thing here, lol !!!