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Everyone should be familiar with standard carbon through-hole resistors, but there are of course other types like wirewound, metal film, metal oxide, etc.

The trouble is, how do you identify the type of resistor if you just have a bunch sitting in a parts bin?

I inherited a grab-bag of parts and haven't been able to identify some components. Here is a sample of the resistor-like parts:

Various resistors

The topmost part is a standard 1/4W carbon resistor. Below that, I believe a metal film or metal oxide. Below that, I am simply not sure. (I think the last part may even be an inductor.)

Is there a standard color coding for these parts to identify the component and its composition?

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  • \$\begingroup\$ I suspect that #3 is a capacitor, not a resistor. All the others are carbon except #2 which is metal film. #5 is carbon-composition. \$\endgroup\$ – user207421 Dec 23 '12 at 8:49
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    \$\begingroup\$ @EJP - I think you mean inductor. I haven't seen axial capacitors like that. \$\endgroup\$ – Connor Wolf Dec 23 '12 at 8:52
  • \$\begingroup\$ @FakeName I have, but I agree it could be an inductor. \$\endgroup\$ – user207421 Dec 23 '12 at 9:12
  • \$\begingroup\$ there are lot of difference. as you know, there are lots of kinds of resistors.... Just read about one by one. or you can find the detailed rating of each resistor. \$\endgroup\$ – user66832 Feb 15 '15 at 21:47
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Resistors cases are usually tan, brown, blue, or green, though other colors are occasionally found such as dark red, dark gray, pink and light green.

Is there a standard color coding for these parts to identify the component and its composition?

Not really however tan tends to be carbon film, whereas a blue/light blue resistor is likely made of metal film. Resistors with 5 or 6 color bands are almost always metal film. Take for example your second resistor, it has 5 bands while the one above it only has 4.

Your items from top to bottom, (The power ratings are just a guess, and the links show a similar item.)

  1. 1/4W 5% Carbon Film Resistor
  2. 1/4W 1% Metal Film Resistor
  3. An Inductor*
  4. 1/4W 5% Carbon Film Resistor???
  5. 1/2W 5% Carbon Composition Resistor

*As @JYelton pointed out, measuring it with an ohmmeter would be definitive in separating resistors from inductors. Inductors wouldn't obey the resistor color code and thus measured resistance wouldn't agree with the markings.

How to Tell the Difference Between Carbon & Metal Film Resistors

Odd colored resistors

Resistor Compositions

Odd Resistors

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Unfortunately, there really isn't any genuinely consistent way to identify resistor composition, short of destructive testing.

However, it is generally true that cheap, carbon-film resistors are usually brown, and metal film resistors are usually blue.
It's also true that it's very rare to find carbon resistors with 1% or better tolerance.

About the only definite thing you can say is that carbon-composition resistors are pretty much universally a straight cylinder with flat ends (like the last resistor in your picture).
Everything else is a guess.


Anyways, for the resistors you posted:

  1. Inexpensive 5% tolerance, probably carbon.
  2. 1% tol, probably metal film
  3. Could be an inductor. That epoxy color is more common for inductors then resistors.
  4. Inexpensive 5% tolerance, probably carbon.
  5. Old-style carbon-composition (not film) resistor. 5%
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  • \$\begingroup\$ I'm ok with destructive testing, as I have a large quantity of all of the above. :) \$\endgroup\$ – JYelton Dec 23 '12 at 9:00
  • \$\begingroup\$ Actually, thinking about it, I think maybe measuring the resistor temperature coefficient would probably be easier, though it would take some fancy equipment. And you still wouldn't be able to nail it down totally, just whether the resistor is carbon-film or metal-film-based. \$\endgroup\$ – Connor Wolf Dec 23 '12 at 9:39
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    \$\begingroup\$ I assume measuring these with an ohmmeter would be definitive in separating resistors from inductors, correct? (Inductors wouldn't obey the resistor color code and thus measured resistance wouldn't agree with the markings.) \$\endgroup\$ – JYelton Dec 23 '12 at 9:42
  • \$\begingroup\$ @JYelton - I think that's a safe assumption. Most inductors that are that size have very small inductance, so trying to measure that without good tools would be challenging (10+ mhz). \$\endgroup\$ – Connor Wolf Dec 23 '12 at 10:00
  • \$\begingroup\$ I thought #3 was for sure a resistor, but on further research I now think it's an inductor, like you said. \$\endgroup\$ – Garrett Fogerlie Dec 23 '12 at 12:08
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4 or 5 rings are hints

Some history, long time ago (vacumn tube to early solid state), composite carbon resistors are popular with 10% tolerance and 4 rings (2 significant digit for value, 1 multipler, 1 tolerance).

Next was carbon film, popular tolerance is 5% and 4 rings.

Next was metal film, popular tolerance is 1% (or even better). 4 rings is not enough and it become 5 rings to add one more significant digit in value.

Above works well for resistor used inside ordinary/low cost consumer products. The last resistor in the photo likely a special carbon composite resistor (based on casing style) of low tolerance. Resistsive element is straight cylinder for this casing and low in inductance and good for rafio frequency use. Film (carbon and metal) are coil structure (add inductance).

You can see the structure by Cutting into half and PEEL off the cover paint. CARE about work safety!!!

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