which is correct?

[Rigor Mortis]

I've inclined to write "twelve months' duration" rather than "twelve months duration." I asked google and, in fairness, it spent a little while thinking and told me both were grammatically correct.

I know people here know better than google.

 

[Homer Potvin]

That one's probably a pick 'em, but I'd go without the apostrophe. In my mind the "twelve months" is functioning more as an adjective phrase describing the "duration" than an object possessing another. Either is probably technically correct though.

 

[Louanne Learning]

I would go a little different. I would turn twelve-month into a compound adjective and so hyphenate it

Then, the noun is duration, so takes a singular article

a twelve-month duration

 

[Also]

I would also have trouble writing it without the apostrophe, as framed. Like the use of perfect aspect where called for, that apostrophe is a (not-so?) subtle indicator of careful correctness.

However, because c-groups (and presumably some readers) often incorrectly flag the apostrophe as a mistake anymore, I often sidestep the issue for them in the way that Louanne suggests.

 

[Naomasa298]

I might be inclined to write "twelve month duration", not months (with or without an apostrophe). Saves one keystroke.

 

[Homer Potvin]

I might be inclined to write "twelve month duration", not months (with or without an apostrophe). Saves one keystroke.

Yeah. I didn't notice that the first time. It's a clunky phrase either way. Seem like a plain old "year" but suffice in most contexts, but not all, obviously.

 

[CatrionaGrace]

I'd probably say, "for twelve months" or "for a year" and eliminate "duration."

 

[Trish]

I might be inclined to write "twelve month duration", not months (with or without an apostrophe). Saves one keystroke.

This is what I would do.

 

[Louanne Learning]

twelve month

This is a compound adjective and needs a hyphen