How to Write and Punctuate Measurements Correctly
(NOTE: This is #1 MOST POPULAR POST on my website TCC6.com)
How to spell out measurements correctly is a hot topic for technical editors and I suspect will remain so for eternity.
Ultimately, there is no absolutely correct and absolutely-wrong way of writing anything. I’ve seen so many different writing guidelines and style books recommending so many different principles that I cannot in all good conscience be an absolutist in this matter.
Yet I also have to admit that there do exist time-honored ways of spelling and punctuation widely used by most technical communicators.
Here is my take on some of them:
No period after abbreviations, except one
Only “in” for inch takes a period afterward, in order to differentiate it from the preposition “in.” Others don’t.
Incorrect
1 cm.
1 in
1 lb.
Correct
1 cm
1 in.
1 lb
Non-breaking space in between a number and the measurement unit
Why?
If your number ends up at the end of a line, the measurement will not appear all alone at the beginning of the next line. It makes sense to keep a number and its unit together, at all times. Thus, the non-breaking space.
To insert a non-breaking space in MS Word (Windows PC), press Ctrl+Shift+Spacebar. On a Mac, press Option+Spacebar.
Leave one space between a number and its unit and do not italicize the unit abbreviation. ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
Incorrect
1cm
1?mm
1lb
Correct
1 cm
1 mm
1 lb