Talk:Litre

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SI prefixes table - more often used terms in bold

How was it decided which units were bolded to indicate they were more often used? I've never heard or seen hectolitre, decilitre, centilitre or microlitre in common usage but have heard and seen kilolitre, megalitre and gigalitre in common usage. GK1 (talk) 00:08, 25 January 2018 (UTC)[reply]

Would Americans say, "I gotta yottaliter - that's a lotta liters"? Mike Spathaky (talk) 22:06, 13 June 2018 (UTC)[reply]

The litre is not a metric unit

Discuss. Dondervogel 2 (talk) 16:40, 10 January 2020 (UTC)[reply]

@Dondervogel 2: "metric unit", as used in this article, redirects to "metric system", suggesting a metric unit is a unit of the metric system, and in that article it says of the metric system: "It is now known as the International System of Units (SI). Given that we know that the "litre" is a "non-SI unit", it follows that it's a non-metric-system unit too. Or is the "metric system" article wrong about that? -- DeFacto (talk). 18:06, 10 January 2020 (UTC)[reply]

The metric system article also says Metric system may also refer to other systems of related base and derived units defined before the middle of the 20th century, some of which are still in limited use today. -Arch dude (talk) 19:30, 10 January 2020 (UTC)[reply]

Very confusing, yes. -- DeFacto (talk). 20:02, 10 January 2020 (UTC)[reply]

@DeFacto: That might be the case now, but you miss an important detail. The link I used was not to Metric system but to Outline of the metric system. That second article explicitly includes the litre in its list of metric units. Why? Because the litre is a metric unit. Period. Dondervogel 2 (talk) 20:42, 10 January 2020 (UTC)[reply]

@Dondervogel 2: that's an annoying WP:EGG link though, and the first thing I did after clicking that was to find and click the first link to where the text led me to believe I would have been taken - to metric system. The fact is, the articles are confusing, contradictory and unhelpful, and need tidying. -- DeFacto (talk). 20:57, 10 January 2020 (UTC)[reply]

@DeFacto: Here we agree. The links are indeed contradictory, and that is because the article metric system conflates metric units with SI units. In reality, the set of SI units is a small subset of all metric units. The errors in that article need fixing but here we are discussing the litre, which remains a metric unit, regardless of what other articles might say about it. Dondervogel 2 (talk) 21:05, 10 January 2020 (UTC)[reply]

@Dondervogel 2: yes, fair comment - I agree. -- DeFacto (talk). 21:14, 10 January 2020 (UTC)[reply]

Great. I'm glad we found common ground. Dondervogel 2 (talk) 10:20, 11 January 2020 (UTC)[reply]

@Dondervogel 2: IMO a litre is a metric unit in the sense that it is/was a formal unit of an older system commonly known as "the metric system" in its time. All we need to do in this article is to make sure we identify the relationship of the litre to the SI, and we do that. The confusion is a matter of which tense , "is" or "was", should be used in an encyclopedic article, and that's messy. See MOS:TENSE. -Arch dude (talk) 19:19, 10 January 2020 (UTC)[reply]

@Dondervogel 2: I modified the wording of the hatnote, which was the very first prose in the article, to no longer call it "the metric unit". -Arch dude (talk) 19:40, 10 January 2020 (UTC)[reply]

What a mess!

It seems we have 4 closely related articles:

In addition we have metric units, which redirects to International system of units. What we need is one article to describe the concept of a general metric unit, which could include some history and would include the litre. And a second one on the SI, which would exclude the litre. The other articles seem redundant to me. Dondervogel 2 (talk) 16:17, 11 January 2020 (UTC)[reply]

I just edited Metric units so that it redirects to Outline of the metric system because that's the only one I could find that makes a distinction between metric units (which include the litre) and SI units (which do not). Dondervogel 2 (talk) 16:26, 11 January 2020 (UTC)[reply]

I agree it's a mess, and there's "Introduction to the metric system" too. It'll be a big job to try and fix it though. Where do we start? Probably not here, in the "litre" article. :) -- DeFacto (talk). 18:01, 11 January 2020 (UTC)[reply]

I agree this is not the most obvious place, but I chose to make the point here to avoid a parallel discussion. How about we first agree (here) where best to take it and then move the discussion to that location? Dondervogel 2 (talk) 18:40, 11 January 2020 (UTC)[reply]

@Arch dude: pinging Arch dude. Dondervogel 2 (talk) 18:42, 11 January 2020 (UTC)[reply]

The three of us might be able to bring some order to this chaos, but I'm a fairly haphazard editor with other interests. Perhaps we should propose a structure and then take it to the appropriate(?) Wikiproject to get more input? My own inclination is to make the SI article the master article, and point to the other articles from its brief overview subsections ("metric systems", "history", etc.) since GIPM specifically mentions litre, it gets included there, but only to say that it's a non-SI unit. -Arch dude (talk) 19:19, 11 January 2020 (UTC)[reply]

That makes sense. How about we post a message at International system of units, making a case for creating a new article metric units and deleting Outline of the metric system, Metric system and Introduction to the metric system. The contents of the 3 deleted articles could be merged into the remaining 3. Dondervogel 2 (talk) 20:32, 11 January 2020 (UTC)[reply]

@Dondervogel 2: that sounds like a step in the right direction to me, as there doesn't seem to be a suitable (active) Wikiproject to take this to. -- DeFacto (talk). 07:06, 13 January 2020 (UTC)[reply]

Alternative suggestion: Might Wikipedia:WikiProject_Physics be a better place to post our message? They already have a discussion going on merging Technical atmosphere with Kilogram-force per square centimetre. Dondervogel 2 (talk) 00:06, 17 January 2020 (UTC)[reply]

That looks like an appropriate, and article-independent, place to put it. I'd support that. -- DeFacto (talk). 07:11, 17 January 2020 (UTC)[reply]

Preparing comment to be posted at WP:Physics

@Arch dude: @DeFacto: Thoughts or suggestions for improvement? Dondervogel 2 (talk) 09:08, 18 January 2020 (UTC)[reply]

Background

A group of editors working at Litre has identified the following closely related articles.

We feel there is too much duplication in these 5 articles. We also see a need for a new article Metric units. That new article could usefully include summaries of

Proposal

Create new article Metric units
Delete existing articles History of the metric system, Introduction to the metric system, Metric system, Outline of the metric system
Merge material from deleted articles into International system of units or Metric units as approproriate.

Support

Oppose

Comments

@Dondervogel 2: looks good to me. -- DeFacto (talk). 21:49, 18 January 2020 (UTC)[reply]

I posted the comment at WP:Physics. Dondervogel 2 (talk) 18:57, 19 January 2020 (UTC)[reply]

I've given up at WP:Physics. They either don't understand or are uninterested in the distinction between the metric system of units (arguably the SI) and the collection of all metric units (which includes the SI and many other metric units). Instead I have made a stub on my user page. Feel free to add suggestions of your own. Dondervogel 2 (talk) 12:56, 10 February 2020 (UTC)[reply]

Well done for trying. We'll just have to keep chipping away at it, and see how it goes. -- DeFacto (talk). 20:38, 10 February 2020 (UTC)[reply]

I uploaded the article from my user page to Metric units. I'm not sure about the logarithmic units though. Perhaps they belong elsewhere - depends what one understands by a "metric" unit. See what you think. Dondervogel 2 (talk) 15:04, 16 February 2020 (UTC)[reply]

What symbol should Wikipedia use for the litre?

If you have an opinion, please express it at this RFC. Dondervogel 2 (talk) 07:43, 28 February 2021 (UTC)[reply]

The litre is not an SI unit

There is only one SI unit of volume, which is the cubic metre. This edit conflates SI and BIPM. It should be reverted. Dondervogel 2 (talk) 10:24, 11 May 2025 (UTC)[reply]

@Dondervogel 2, yes, I think most of us know about cubic metres. This article is about the litre though, and not the cubic metre, and, "L" and "l" are symbols specified by the BIPM in their SI brochure, which they say, "defines and presents the Système International d’Unités". And in that definition of the SI they have specified "L" and "l" as the "allowed" symbols for the litre, hence they are SI symbols for the litre. Compare them with "ltr" and "ℓ" which are also commonly used to represent litres, but which are not specified in the SI 'brochure' as "allowed" symbols, and so are not described in this article as SI symbols. -- DeFacto (talk). 11:40, 11 May 2025 (UTC)[reply]

Specifying "SI" does seemingly create opportunities for our readers who may not be so well-established on these things to draw a wrong inference or encounter other confusions though—and for no real benefit to readers other than frontloading the abstract ontology found in the SI brochure.

It shouldn't be in the lead sentence, don't think. Remsense ‥ 论 11:51, 11 May 2025 (UTC)[reply]

Why mislead though when we can be specific? If we just list the symbols without qualifying their status, we'd have to include the non-SI symbols in the same list - "symbols l, ℓ, L and ltr"? No, I favour keeping the SI ones separate, and correctly attributing them. -- DeFacto (talk). 12:41, 11 May 2025 (UTC)[reply]

Maybe this is a good opportunity for a footnote, merely explicating the useful background knowledge we've laid out above? Remsense ‥ 论 12:49, 11 May 2025 (UTC)[reply]

(edit conflict)It's fine to specify that "L" and "l" are the SI symbols, not just WP editors' choice; they're the symbols adopted by the CGPM (not the BIPM) for the unit which "must be admitted for general use with the System" (more fully, "considering that the name litre, although not included in the Système International d’Unités, must be admitted for general use with the System, decides, as an exception, to adopt the two symbols l and L as symbols to be used for the unit litre").^[1] Thus, although the unit is not an SI unit though accepted for use with the SI, those are the symbols adopted by SI's supreme governing body for its use with SI. We expand on the status of these symbols at length in both Litre#Symbol and Litre#History, so there's no need to go into detail in the lead too nor even to provide an explanatory footnote; as ever, our priority is to ensure the lead gives the basics in a nutshell, introduces the article, and cultivates interest in reading on. NebY (talk) 13:19, 11 May 2025 (UTC)[reply]

References

^ The International System of Units (PDF), V3.01 (9th ed.), International Bureau of Weights and Measures, Aug 2024, p. 174, ISBN 978-92-822-2272-0

References

[1] The International System of Units (PDF), V3.01 (9th ed.), International Bureau of Weights and Measures, Aug 2024, p. 174, ISBN 978-92-822-2272-0

[1]