ml or mL

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Senior Member
Galician and Spanish (Spain)
Hello! I have always though that the correct abbreviation for millilitre was "ml" but I have found a lot of sources using "mL". What I have not found is any reliable source stating which one is the best option. Is it related to the country where it is used or is it completely random? If it is the first case, I would like to know which is the most used form in UK English. Thank you!
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    Senior Member
    British English

    This Wikipedia article uses "mL" but the context seems rather specialist.

    On commercial products (for example drinks) I see "ml".

    I also looked at several maths and science sites, and all seemed to use "ml".
    Last edited:


    Senior Member
    English (UK then US)
    In many US publications the L is the required form (see American Chemical Society's pdf and IEEE's pdf) and the styles of those organizations are used in style guides for many other publications. Many people had used lower case l for so long that the SI made an exception for it. Wiki has an entry for litre (liter) and footnote 1 has a link to a pdf from the SI (Systeme Internationale - wiki) where many of these issues are defined/decided/curated.

    Unit symbols are printed in roman (upright) type regardless of the type used in the
    surrounding text. They are printed in lower-case letters unless they are derived from a
    proper name
    , in which case the first letter is a capital letter.
    An exception, adopted by the 16th CGPM (1979, Resolution 6), is that either capital
    L or lower-case l is allowed for the litre,
    in order to avoid possible confusion between
    the numeral 1 (one) and the lower-case letter l (el).
    So upper case l is "allowed" but not everyone adheres to the rulings of the SI body. I couldn't find any UK based publication group's preference but IUPAC (International Union of Pure and Applied Chemistry) is also used a source of standard recommendations on these matters and is in line with SI.

    That said, I have seen the "cursive" little l (ℓ) used in text where there is no other cursive specifically to indicate litre. Thus the lower case l can be used but will not be confused with 1 :D As for "non-scientific" uses of the letter, I'll have to leave it to UK residents to report on their experiences of usage and the form than any UK authorities deem to be "correct". I found an EC website that uses lower case l for litre ( and there's probably a document from them on the issue. Then, we need to know: would the average UK user follow the EU guidelines anyway???


    Moderato con anima (English Only)
    English (Singapore/UK), basic Chinese
    I see ml from UK sources, but have noticed mL in Australian and American packaging. My old maths textbook had the loopy version mentioned by JulianStuart - mℓ. I don't really see an issue if you're writing ml or cl. The issue is writing 1 l for example and I suppose 1 L or 1 ℓ would be clearer.


    Senior Member
    I live in the UK and as far as I am aware, I have never seen it written as mL.
    Anyway, as it has been already pointed out, Wikipedia uses the variation mL.
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