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Are "ins", "hrs", "mins" and "secs" the technically correct plural abbreviations for "inches", "hours", "minutes" and "seconds"? I'm hoping that all examples below could possibly be correct.


Plural: He finished the race in 4hrs 34mins 9secs.

Singular: His 4hr 34min 9sec finish was unprecedented.

Plural of 'inches': Garry was 5ft 10ins tall.

Singular of 'inches': Garry was a 5ft 10in man.

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You also have ' and " as in 5'10" which has also been used for minutes and seconds (both time and measure kind) –  mplungjan Feb 27 '14 at 13:54
@mplungjan strictly ′ and ″ as in 5′10″. While the straight single- and double-quote we use for the typists convenience are a reasonable substitute in many cases for the prime and double-prime that abbreviate feet and inches, if the one is interested in being strictly correct, as it would seem the OP is, then ′ and ″ should be used. –  Jon Hanna Feb 27 '14 at 15:09

2 Answers 2

IUPAC (see section 1.3) and NIST sanction that "unit symbols are unaltered in the plural".


In the comments, oerkelens makes the distinction between unit symbols and abbreviations. Unit symbols are attached to a number to define its units, e.g. 5ft 10in, and abbreviations can be used independently, e.g.:

  • How many "secs" have we left?

I agree with oerkelens that the above use can be found in colloquial conversations.

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SI unit symbols. The only SI unit in the OP is the second, its unit symbol is s. So I don't see how these links are relevant to the OP's question? –  oerkelens Feb 27 '14 at 14:37
@oerkelens My understanding is that IUPAC recommendations are not limited to SI units. This is the reason why I didn't give a link to the BIPM. –  Nico Feb 27 '14 at 14:45
Ok, I looked at NIST first. But still, the OP asks about commonly used abbreviations, not about unit symbols. sec is not the unit symbol for second, so whether the unit symbol s changes in the plural or not, has no bearing on whether sec changes or not :) –  oerkelens Feb 27 '14 at 14:49
@oerkelens OK, I understand your point, but I would argue that some of the examples the OP quotes are uses of units, e.g. 5ft 10in vs 5ft 10ins, and some people would frown upon the use of the plurals in those cases. –  Nico Feb 27 '14 at 14:55
I would actually not use plurals in the OP's examples, but I think the official SI rules (and the likes) are the wrong argument for it. –  oerkelens Feb 27 '14 at 14:56

The SI unit for time is Seconds (s). Hours (h) and minutes (min) are accepted to be used within the SI even if not standardised. In scientific writing you should probably stick to those abbreviations (note that it's 60 min not 60 mins).

In common usage all your examples should be understandable. As is, for instance, the 5'10" style for feet-inches

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So, technically, do these revised versions somewhat fit the criteria? No recasts, please. Plural: He finished the race in 4h 34min 9s. Singular: His 4h 34min 9s finish was unprecedented. –  whippoorwill Feb 27 '14 at 14:49
My boss asked me about this (using the abbreviated format), so I want to be accurate to the nth degree. –  whippoorwill Feb 27 '14 at 15:25
You should use a space between the number and the unit (source), except in the case of the prime and double prime. (The NIST page doesn’t address those in the context of inches and feet, since scientific writing does not use inches or feet, but they do say not to use a space before the prime and double prime in the context of minutes and seconds of angle.) –  bdesham Feb 27 '14 at 17:29

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