This question:

Why do many electronics operate on 5 AND 3.3 Volts?

(Worded "Why do many electronics operate on 5 AND 3,3 Volts?" in case it gets edited.)

Recently reminded me of the frustration of working with electronics on an international scope. Some countries use period/full-stop for the decimal mark, others use the comma.

I read up a little on this at Wikipedia:


"International" languages like Ido and Esperanto favor use of the comma for the decimal mark. I was surprised by this, because I find the comma more distracting in numbers when reading with text.

In any case, my question/proposal is thus:

Does StackExchange (specifically EE) have any preference or standardization when it comes to the decimal mark? Which is ultimately more common? (Obviously I would be biased if I said the period/full-stop seems to be more common, as I am in the US.)

Should SE/EE standardize on one or another, so as to not mix formats?


Whether the point or comma is used between the integer and fraction digits is defined by each language. For example, in english it is the point, and in german the comma.

There is therefore only one correct choice when the language is known. This site is in english, so obviously the point is the only correct character when used in text here.

In unusual cases we have to post diagrams and the like here that are language-independent or don't have a obvious language context. In that case it is ambiguous and we have to be careful how things are interpreted. Fortunately if there is only one of comma or point in a number it's pretty obvious what the meaning is. No, SE should not dictate this because it would make it impossible to correctly post diagrams or schematics from elsewhere that we may not have control over.

However, the title of the question you linked to is just plain wrong. It is clearly in english, so it should have used a point. I'll go fix that now.

  • 3
    \$\begingroup\$ "However, the title of the question you linked to is just plain wrong. It is clearly in english, so it should have used a point. I'll go fix that now." - I read this and I just had to laugh. \$\endgroup\$
    – Kortuk
    Oct 12 '12 at 13:05

I'm in Belgium, where (both in Dutch and French) a comma is used for decimal mark, and dots as grouping marks (grouped per 3 digits before the decimal). However, since my college time I've been immersed so deep in textbooks, manuals and datasheets in English that I use the US/UK standard. Sorry for my compatriots, but that's the way it is. EE.SE is a site where English is the lingua franca (and most users are in the US?), so I think we should standardize to a dot for the decimal.

ISO-31 allows both comma and dot for the decimal, and then of course they get into trouble. (Do these guys really get paid for their work?): they can't use either as a group separator. That not very often a problem here: for component values we use multipliers like "M" for mega- or "k" for kilo-, and then you won't see more than 3 significant digits very often. ISO-31 recommends a "small space" as a separator. Yeah, right, do you have that on your keyboard? (I don't.) Wolfram Mathematica does add "small spaces" in notebooks, but when you copy the number and paste it in a common editor (or here) the spacing is lost. Using a common space character has the disadvantage that a carriage return may break the number, unless you're prepared to use & nbsp; HTML codes all the time. (I'm not.)

So, for me:

  • A dot as decimal mark
  • No grouping separator
  • 1
    \$\begingroup\$ Re: the throwaway remark "Do {the ISO} guys really get paid for their work?" the answer is No... you don't (usually) get paid for committee work :) \$\endgroup\$
    – Andrew
    Oct 19 '12 at 13:47

I use el cheapo ball points at home that often just refuse to write a . (dot). So I am used to write 3V3 and 2k\$\Omega\$7.

OK, I agree that 17kWh371 looks interesting, so I guess in that case I'm back to using dots for decimal separators (17.371 kWh), because the site is en_US.

I agree with Olin that (EE.)SE cannot dictate a standard, too many people from too many countries use SE and in most cases it is obvious what the author meant and it just is not worth the effort to edit all questions, answers and diagrams.

  • \$\begingroup\$ I think I personally prefer a hard space as grouping separator because it does improve readability without introducing confusion. On the other hand if I need more than 3 digits to write a number it usually is way too accurate to be useful anyway so I rewrite the number with a decimal prefix. \$\endgroup\$
    – jippie
    Oct 27 '12 at 8:08

As more and more engineers function in global roles, a little reminder now and then that not everybody across the world writes numbers the same way is a good thing. Best to see it here and now than in a failure mode analysis!


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