We know that $25.00$ in English is actually written as $25{,}00$ in French (and many other languages actually). Weird, but true!

Now, non-anglo users frequent our site and often write in such notation. While removing tags from old posts, I have swapped the , with a . at least ten times, until now I realized I should ask about this on meta first to reach a consensus.

This is the latest occurrence of such a conversion. In such cases, should I:

  1. convert the comma to a decimal?
  2. leave the comma as it is?

I am actually in favor of the first way as SE in general has majority of its visitors from these countries (but I don't know of Chem.SE specifically?), so it makes sense to do it the way it is for the majority of the people. I would wish to hear other views though, as there are surely use-cases I might have missed.

  • $\begingroup$ Dot dot dot ........... $\endgroup$ Feb 26, 2018 at 13:49
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    $\begingroup$ Not only in French; actually most countries use a comma as the decimal sign. $\endgroup$
    – user7951
    Feb 26, 2018 at 13:51
  • $\begingroup$ @Loong Oh, that's cool, I corrected accordingly $\endgroup$ Feb 26, 2018 at 13:57
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    $\begingroup$ This ... is a really good question. AFAIK the official language of SE sites is English, so that's probably why the Anglophone convention for decimal/comma use has been in place ($20,000.00$, rather than $20.000,00$). We've discussed American vs British spellings before, but I've never seen any explicit discussion of this. $\endgroup$
    – hBy2Py
    Feb 26, 2018 at 15:14
  • $\begingroup$ If somebody wrote "natrium" in a question, we'd edit it to "sodium" without question, and similarly for any other foreign word. I think we should do the same for foreign numerical representations. Indeed, it seems more important for numbers, since there's much more scope for misunderstanding. $\endgroup$ Mar 10, 2018 at 18:40

1 Answer 1


I would say: Yes, convert to English-language numerical punctuation.

The official language of the Stack Exchange network is English, save for sites whose mission is specifically to provide content in other languages. This has been established via this Meta.SE post, and the SO blog post linked there.

Therefore, it makes the most sense to me that numerical values should be consistently formatted according to English-language conventions: $12{,}345.67$, not $12.345{,}67$ or anything else. The main exception would be for material quoted from another source that uses a different syntax convention—in that case, it would make sense to leave the numbers formatted as they are in the original source.

Implicitly, the Meta.SE post could be argued to support this view: about halfway down, it reports some numbers and uses a period as the decimal marker:

The number of people who speak English is nowhere near as important as how many people can write it. More specifically, the number of people who use their written language on the Internet can be the single most telling piece of information. The #1 language of the Internet is English, by a wide margin. In the chart below you can see that it is almost three times as prolific as the next language.

Global Internet Usage
Language - Number of users (millions)

English - 295.2
Chinese - 110.0
Spanish - 86.0

  • $\begingroup$ Thanks for your answer! :) I agree with your view. The list of countries that use the comma as a separator is Swedish, French, German, Italian, etc. - i.e. non-English speaking countries only. Since StackExchange is an English speaking "country" (well at least this community is more populated than several other countries of the world :P), so the dot separator should apply, not the comma. $\endgroup$ Feb 26, 2018 at 16:38
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    $\begingroup$ Note that according to ISO as well as The International System of Units (SI), where separation into groups of three digits is used, the groups shall be separated by a small space and not by a point or a comma or by any other means; i.e. write $12\,345.67$ rather than $12{,}345.67$. $\endgroup$
    – user7951
    Feb 26, 2018 at 16:48
  • $\begingroup$ @Loong But, do we use the English conventions or the SI conventions for this matter? I think this is a borderline case, as the separation of three-digit-groups by a space/comma falls under the jurisdiction of both the SI units (as you said) and the English language. Both have opposite recommendations, so which to choose? $\endgroup$ Feb 27, 2018 at 4:49
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    $\begingroup$ @GaurangTandon I don't think we need to specify English or ISO as a strict convention. mwchem has conveniently included the ISO half-space separator in the \pu "physical units" helper command within the mwchem \ce environment: $\ce{\pu{20000}}% $\rightarrow \ce{\pu{20000}}$. So, in math and formulas, where the ISO formatting is easily available, one can use that. In regular text, where a half-space is hard to achieve, sticking with the English "20,000" would be fine. $\endgroup$
    – hBy2Py
    Feb 27, 2018 at 11:46
  • $\begingroup$ Yes, that sounds helpful @hBy2Py :) $\endgroup$ Feb 27, 2018 at 11:47
  • $\begingroup$ Consider adding Loong's update into your answer. I'll accept your answer within a week until there any contradictory views. $\endgroup$ Feb 27, 2018 at 11:47
  • $\begingroup$ @GaurangTandon Yep, will do,, I was planning to edit it into the answer after a bit as long as there wasn't any major pushback. $\endgroup$
    – hBy2Py
    Feb 27, 2018 at 11:50
  • $\begingroup$ @GaurangTandon I'd suggest that editing to "correct" English to ISO is basically the same as editing to "correct" British to American spelling (or vice-versa). $\endgroup$ Mar 10, 2018 at 18:42

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