# For measured quantities, should there be a space between the number and its units? **URL:** \ **Category:** Factual Questions\ **Created:** [April 4, 2003, 4:40pm UTC](https://boards.straightdope.com/t/for-measured-quantities-should-there-be-a-space-between-the-number-and-its-units/166489 "2003-04-04T16:40:47Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [April 4, 2003, 4:40pm UTC](https://boards.straightdope.com/t/for-measured-quantities-should-there-be-a-space-between-the-number-and-its-units/166489/1 "2003-04-04T16:40:47Z")
I have a co-worker who goes on a rampage when someone does not put a space between the number and its units. For example, he claims “72°F” is **wrong, wrong, wrong**. He says there’s a standard in the U.S. military that requires a space between the number and its units, i.e. “72 °F” is more correct. So I thumbed through some of my technical books. Two which I consider rather authoritative – _The ASHRAE Handbook_ and _The Art of Electronics_ – do not put a space between the number and units. I also checked my electronics textbook from college; it _does_ put a space between the number and units. So what’s the deal? Is there a standard convention? I’m thinking it could also depend on the units, e.g. 72°F looks O.K. to me, but 25m[sup]2[/sup] looks kinda funny. ---
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [April 4, 2003, 4:50pm UTC](https://boards.straightdope.com/t/for-measured-quantities-should-there-be-a-space-between-the-number-and-its-units/166489/2 "2003-04-04T16:50:04Z")
Actually, “72° F” looks more “correct” to me. Special symbols like degrees or ’ or " for “feet” and “inches” don’t get spaces, abbreviations for words do. I’m sure there’s a style guide somewhere. I’m not quoting it. ---
**Author:** ![Surreal](https://avatars.discourse-cdn.com/v4/letter/s/eada6e/32.png) [@Surreal](https://boards.straightdope.com/u/Surreal)\ **Post date:** [April 4, 2003, 5:01pm UTC](https://boards.straightdope.com/t/for-measured-quantities-should-there-be-a-space-between-the-number-and-its-units/166489/3 "2003-04-04T17:01:13Z")
Yes, there needs to be a space. [http://216.239.39.100/search?q=cache:\_ulGwkiNbHsC:www.usaid.gov/pubs/ads/300/fstd376b.doc+ANSI+PREFERRED+UNITS+KELVIN+SPACE&hl=en&ie=UTF-8](http://216.239.39.100/search?q=cache:_ulGwkiNbHsC:www.usaid.gov/pubs/ads/300/fstd376b.doc+ANSI+PREFERRED+UNITS+KELVIN+SPACE&hl=en&ie=UTF-8) “_SI units are always written in an upright typeface with a space between the numeric value and the symbol. See ANSI/IEEE Std 268 and other documents listed in the Bibliography for further usage rules._” ---
**Author:** ![Surreal](https://avatars.discourse-cdn.com/v4/letter/s/eada6e/32.png) [@Surreal](https://boards.straightdope.com/u/Surreal)\ **Post date:** [April 4, 2003, 5:02pm UTC](https://boards.straightdope.com/t/for-measured-quantities-should-there-be-a-space-between-the-number-and-its-units/166489/4 "2003-04-04T17:02:46Z")
The link worked in ‘Preview’, but it doesn’t work now. I don’t know what happened. ---
**Author:** ![Kalashnikov](https://avatars.discourse-cdn.com/v4/letter/k/2bfe46/32.png) [@Kalashnikov](https://boards.straightdope.com/u/Kalashnikov)\ **Post date:** [April 4, 2003, 5:37pm UTC](https://boards.straightdope.com/t/for-measured-quantities-should-there-be-a-space-between-the-number-and-its-units/166489/5 "2003-04-04T17:37:03Z")
The CRC math handbook uses “20°C” and “20 mV”, but 25mV or 12VDC look ok to me. National Semiconductor’s datasheets use a space. Motorola’s don’t. Analog Devices’ do. Phillips’ do. ---
**Author:** ![milquetoast](https://avatars.discourse-cdn.com/v4/letter/m/258eb7/32.png) [@milquetoast](https://boards.straightdope.com/u/milquetoast)\ **Post date:** [April 4, 2003, 6:48pm UTC](https://boards.straightdope.com/t/for-measured-quantities-should-there-be-a-space-between-the-number-and-its-units/166489/6 "2003-04-04T18:48:43Z")
I’d say you’ve answered your own question. There is no one standard convention because it’s a style issue. And style issues are up to the body governing the publication. The military may have one dictate (and it sounds as if they do given your coworker’s strong opionion), but other governing bodies (institutions, academic socities, whatever) may choose to use a different style. Having worked for a company that typeset college textbooks, I know different publishing companies have different styles. So while the colloege textbook you referenced has a space, a textbook published by a different company may not. ---
**Author:** ![Omphaloskeptic](https://avatars.discourse-cdn.com/v4/letter/o/bcef8e/32.png) [@Omphaloskeptic](https://boards.straightdope.com/u/Omphaloskeptic)\ **Post date:** [April 4, 2003, 9:50pm UTC](https://boards.straightdope.com/t/for-measured-quantities-should-there-be-a-space-between-the-number-and-its-units/166489/7 "2003-04-04T21:50:41Z")
For typesetting questions, Donald Knuth’s TeX is a pretty good guide. The TeXbook says: > [@](#): > > When physical units appear in a formula, they should be set in roman type and separated from the preceding material by a thin space. For TeX, a “thin space” is 1/6 of a quad, about half a normal space (a quad is the width of an M). Degrees are a somewhat special case: degrees in angle are typeset without the space, but for degrees of temperature the space is often present. ---
**Author:** ![tomndebb](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tomndebb](https://boards.straightdope.com/u/tomndebb)\ **Post date:** [April 4, 2003, 10:01pm UTC](https://boards.straightdope.com/t/for-measured-quantities-should-there-be-a-space-between-the-number-and-its-units/166489/8 "2003-04-04T22:01:09Z")
**Surreal** , your link had a secondary reference to a web site (since it was apparently the result of a search) and the vB code parsed both the “http” and the “www” Your intended link was: [Federal Standard 376B](http://216.239.39.100/search?q=cache:_ulGwkiNbHsC:www.usaid.gov/pubs/ads/300/fstd376b.doc+ANSI+PREFERRED+UNITS+KELVIN+SPACE&hl=en&ie=UTF-8) (You have to uncheck the **Automatically parse URLs:** Option on the reply screen to use a Google cached page.) Alternatively, don’t use the Google cached page, and link directly to the original: [http://www.usaid.gov/pubs/ads/300/fstd376b.doc](http://www.usaid.gov/pubs/ads/300/fstd376b.doc) (which, in this case forces a Word Document download, so I can see why you avoided that option). ---
**Author:** ![Giraffe](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/giraffe/32/129_2.png) [@Giraffe](https://boards.straightdope.com/u/Giraffe)\ **Post date:** [April 4, 2003, 10:02pm UTC](https://boards.straightdope.com/t/for-measured-quantities-should-there-be-a-space-between-the-number-and-its-units/166489/9 "2003-04-04T22:02:39Z")
In my experience, scientific publications almost always put a space. For example, I have probably fifty physics papers on my desk, from jounrals like Physical Review Letters and Journal of Chemical Physics, and they all have spaces. Electronics is one field where the space is most often omitted, in my experience, probably for some practical reason. I’m not sure if there is an absolute convention, but it’s rare not to have a space in a scientific publication. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [April 4, 2003, 10:05pm UTC](https://boards.straightdope.com/t/for-measured-quantities-should-there-be-a-space-between-the-number-and-its-units/166489/10 "2003-04-04T22:05:07Z")
Butterworth’s _Electrical Engineer’s Reference Book_ puts a space between the quantity and the units, except for temperatures. Same with Cassell’s _Linear Electric Circuits_ and Nobleman and Smith’s _Mathematics for Electronics_.