Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Is there a simple way to tell axial inductors and resistors apart in through-hole type PCBs? I do find the color code on both very confusing. Is there an obvious difference that I am missing? As a beginner, I might just be overlooking something very simple.

share|improve this question
There is no universal reliable way. Most of the time you just know, or keep your stock properly labeled. – Olin Lathrop Apr 27 '14 at 12:15
Why not test for continuity with a multimeter? – sebascarra May 13 at 23:29

Axial inductors tend to be sea foam green, although some are pea green or even cyan. The cyan ones you can tell from 1% resistors because they have one fewer band.


share|improve this answer
Also, I don't know if all axial inductors have these, but the ends are more "pointy" than resistors – NothingsImpossible Apr 27 '14 at 11:26

The easiest, and most reliable, way is to look at the designator (and on a through-hole board, there is almost always a printed designator). If it says "L3", for example, it's most likely an inductor. If it says something like "R37", on the other hand, it's probably a resistor!

Beyond that, resistors sometimes have a specific body color, as Ignacio says, but not always. Dipped axial-lead inductors tend to have a specific kind of 'lumpy' look because of the wire, whereas resistors are fairly regular in their midsection.

enter image description here

I suggest you go to a parametric search engine such as Digikey's, and search for a common value of axial-lead inductor (10\$\mu\$H will do) and look at the photos (you can mouseover the pictures to get a better view (more-or-less ignore the ones that are obvious 3D renderings of ideal 3D models). You can see that some are dipped as the photo above, some are molded like the old carbon-composition resistors, and some have a bit of shrink wrap around them. Here is a search that I did, not sure how long it will work, but with "in-stock" and "bulk + cut tape" restrictions, there are only two pages of parts, so you can look at all the variations in a couple of minutes, and quickly gain the kind of experience that would have taken many years not so long ago (and might still not have been exhaustive).

enter image description here

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.