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What is the difference between U+2044 ("Fraction Slash") and U+2215 ("Division Slash").

They seem nearly identical to me, but there's still clearly a difference, but I can't tell exactly what it is.

Does anyone know?

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  • Considering that only the latter falls under Mathematical Operators whereas the former is classified under General Punctuation, I suppose the former is to be used when you want to write something like X or Y or Z (X/Y/Z).
    – Karan
    Jun 1, 2015 at 3:50
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    @Karan The former is for fractions. I think it's in the general punctuation block because it can be used in nonmathematical contexts, e.g. "1/2 cup of olive oil", even though I suppose you could use it in mathematical contexts as well (although it actually seems relatively rare to use that style of fraction in formal formulas). SOLIDUS (forward slash on your keyboard) would be the semantically correct character for separating items.
    – Jason C
    Jun 1, 2015 at 3:54

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The difference between the two is semantic:

  • DIVISION SLASH is in the mathematical operators block. It is intended to be used when representing the mathematical division operator, e.g. in mathematical formulas. Use it when you might say, out loud, "1 divided by 2" or "x divided by y". It is also intended to be used in large fractions in mathematical contexts where the separator is horizontal.

  • FRACTION SLASH is in the general punctuation block. It is intended to be used when representing a fraction. Use it when you might say, out loud, "one half". You might use it in nonmathematical contexts, e.g. "1⁄2 cup of olive oil". In mathematical contexts it is intended to be used for fractions where the separator is skewed.

Hypothetically, having a difference between the two allows for the possibility of correct formatting for different situations, e.g. "1 FRACTION SLASH 2" could be rendered with a superscript 1 and a subscript 2 as 1/2. In practice this generally doesn't seem to be the case, but that capability was the original intent. From section 2.1 of Unicode Technical Note 28:

... the “fraction slash” U+2044 ... builds up to a skewed fraction, the “division slash” U+2215 ... builds up to a potentially large linear fraction, ...

Here is a test, using SOLIDUS (U+002F), DIVISION SLASH (U+2215), and FRACTION SLASH (U+2044) in order (the following character sequences aren't necessarily semantically appropriate, the intent is only to illustrate rendering):

  • Superscript + subscript: 1/2 1∕2 1⁄2

  • Normal: 1/2 1∕2 1⁄2

Depending on your browser and font you may or may not see a difference in rendering above. On my system, DIVISION SLASH and FRACTION SLASH render identically, although differently from SOLIDUS. They have a narrower spacing than SOLIDUS and look better with the superscript/subscript numbers.

For example, a comparison of the rendering in Chrome vs Internet Explorer / Edge is shown below:

rendering in chrome vs internet explorer

The advice I would give to you is this: If you are representing data and wish to be semantically accurate, use DIVISION SLASH and FRACTION SLASH appropriately. However, if you are typesetting and the rendering of either is giving you problems, or in casual communication, or in the presence of general doubt, just use SOLIDUS (the forward slash on your keyboard) instead. Also, if you are typesetting complex mathematical formulas, you may wish to consider using TeX or another dedicated typesetting system.

Further reading:

(And don't worry, I can't actually type this fast. I already typed up an answer waiting for you to ask this.)

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    I would like to improve this answer with a mention of CIRCLED DIVISION SLASH (U+2298) and maybe a bit more about U+002F, but I am not sure when I will have the time to do it. Hopefully soon.
    – Jason C
    Jun 1, 2015 at 4:22
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    Small addendum: Unicode has encoded some common fractions, like U+2154 ⅔. They have a decomposition mapping containing U+2044: <U+2154> → <U+0032 U+2044 U+0033>. That might illustrate, too, how U+2044 is meant to be used.
    – Boldewyn
    Jun 1, 2015 at 7:36
  • "On my system … render identically" What system are you referring to here? On OS X Yosemite, they render slightly differently in everywhere I can test (Safari, Pages, etc), but I don't have a Windows machine or tablet/etc to test on right now. (and by slightly I mean a few antialiasing pixels different on my @2x display—still nothing major but also still noticeable without Retina without zooming in on the above text)
    – grg
    Jun 1, 2015 at 21:34
  • @grgarside I am referring to ... mine. The specifics aren't important, it's an example of one possible outcome. Your mileage may, and probably will, vary. (But, actually, it's a Windows 7 machine with Chrome 43 and a general configuration that has shown itself to have poor support for many characters in the past compared even to other Windows 7 setups.)
    – Jason C
    Jun 1, 2015 at 22:01
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    Things have changed now so that some browsers (Chrome, Firefox) and some other programs implement the idea that digit sequences separated by FRACTION SLASH are formatted as a fraction (like ½), using HarfBuzz software.
    – Jukka K. Korpela
    Jan 12, 2017 at 18:06
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In typrography, both look the same. Fraction slash is to denote FRACTIONS. division slash is DIVISION. In math: Fraction slash: 1⁄2=0.5 Division slash: 1∕2=0.5

HardToTell

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