I'm not an expert in this matter, so AFAIK the most part of electronic components have numeric values while resistors and few other components have colors: why is that? Why there is not a standard for all electronic components establishing the use of values everywhere? I know there are a bunch of very interesting opinions out there (for example Why do resistors still use color coding?), so I'm not looking for one more "opinion" based on personal intuition or needs, but for something more, a kind of "Official" answer.

Would not it be better to have a unique standard method for indicating values of any kind of components expressing them the same way (using just numbers everywhere or just colors everywhere)?

I'm thinking to people that is color blind: isn't better to have just values indicated by numbers and letters to make them able once for all to not confuse a color with another? IMHO this would be in general a better way to go.

PS: If some one votes down please specify why exactly, thanks in advance.

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    \$\begingroup\$ The coloured resistors are smaller have been around a lot longer than the newer numeric labelled parts. Back then, it was difficult to print numbers on such small components. Why is it still used? Because it was used before =/. \$\endgroup\$
    – DKNguyen
    Feb 27, 2019 at 23:08
  • \$\begingroup\$ @Toor: so it is just for "tradition"? \$\endgroup\$ Feb 27, 2019 at 23:10
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    \$\begingroup\$ In SMD, resistors have numbers and capacitors have no markings at all! \$\endgroup\$
    – Dave Tweed
    Feb 27, 2019 at 23:34
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    \$\begingroup\$ The conversation about keyboard layouts is completely irrelevant to the question. Take it to chat. \$\endgroup\$
    – Dave Tweed
    Feb 28, 2019 at 1:17
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    \$\begingroup\$ @willywonka There used to be cases where for example orientation was CBE and BCE so some things were not standard to teach in textbooks. EXPERIENCE comes from reading datasheets. While colour codes were standardized 100 yrs ago then enhanced with higher significant figures for resistors . Semiconductors on the other hand use simple unique OEM codes which due to small size is used for SMD CODES which you can find \$\endgroup\$ Feb 28, 2019 at 1:44

2 Answers 2


According to Wikipedia,

Color bands were used because they were easily and cheaply printed on tiny components.

Resistors are not the only part, for which color-code is used. It is also used for some ceramic capacitors.

IMHO it is much easier to indicate the value of a cylindrical resistor on PCB when it is colored, than with the value written on it, since it does not have the top or bottom side.

For SMT parts people use printed value because SMT part has defined the top and the bottom side, so the text is always visible.

  • \$\begingroup\$ Maybe here you can get "official" version en.wikipedia.org/wiki/… \$\endgroup\$
    – litvinik
    Feb 27, 2019 at 23:11
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    \$\begingroup\$ You should post that link in your answer, for a more 'complete' answer. ALWAYS highlight quoted material and ALWAYS list the link(s) that you used. \$\endgroup\$
    – user105652
    Feb 27, 2019 at 23:29
  • \$\begingroup\$ This is what I was looking for, thanks. I just want to add some more infos from the same source you cited (Wikipedia): "However, there were drawbacks, especially for color blind people. Overheating of a component or dirt accumulation may make it impossible to distinguish brown from red or orange. Advances in printing technology have now made printed numbers more practical on small components." \$\endgroup\$ Feb 28, 2019 at 1:43
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    \$\begingroup\$ @willywonka I could be mistaken but I believe the letter code is now burned in with a laser, much like the letters and symbols on your keyboard. Color codes are done with 2-part epoxy, which is immune to most solvents. \$\endgroup\$
    – user105652
    Feb 28, 2019 at 2:10

You are wrong, there are some film or ceramic capacitors whose value is color-coded, as well as some inductors.

Moreover, SMD resistors have digit-coded values.

  • \$\begingroup\$ Thank you so much for pointing this fact out, I didn't know: I've updated the question. Nevertheless I'm afraid this doesn't count as answer, maybe it would be better as a comment. Thanks anyway. \$\endgroup\$ Feb 27, 2019 at 23:08
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    \$\begingroup\$ Also inductors sometimes have color dots or bands instead of text. \$\endgroup\$ Feb 27, 2019 at 23:08
  • \$\begingroup\$ And many SMD parts have no value code at all, which is a pain when reverse-engineering things. \$\endgroup\$
    – Hearth
    Feb 27, 2019 at 23:23
  • \$\begingroup\$ Resistor-shaped inductors have colour codes. \$\endgroup\$
    – user253751
    Feb 27, 2019 at 23:38
  • \$\begingroup\$ Mica capacitors used to have SIX colored dots, in 2 rows. \$\endgroup\$ Feb 28, 2019 at 3:58

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