We’re all Rolling Stones fans here, right? I mean, we’re all here on a grammar blog, so I don’t think I’m jumping to too wild a conclusion to assume that we’re almost all oldsters, whether in actual age or personality. So let’s talk about the classic “Get Off of My Cloud”:
As it turns out, the Stones weren’t terribly fond of this song; they felt it was a rushed follow-up to the runaway success of “Satisfaction”. But some grammar peevers dislike it for an unrelated reason:
“‘Off of’ is no way to talk. It IS really, really bad English.”
Hatred of off of is widespread. It pops up commonly in peeve lists. Some professional grammar commentators share this complaint: the quote above is from Patricia O’Conner of Grammarphobia*, and Grammar Girl tersely dismisses it with “You jump off the pier, not off OF the pier”.
So what’s supposedly wrong with off of? The main problem seems to be that the of is unnecessary, but another common one is that since it’s on and not on of, it must be off and not off of. I also see complaints that it’s dialectal or informal or American, that one can’t put two prepositions next to each other, or that it ought to be from. And worse, given all of these problems, the phrase is supposedly spreading.
Let’s take these in reverse order. First, I’m unconvinced that it’s spreading, unless you’re talking about a very recent (last 20 years) spread. Here’re the Google Books counts, and you’ll note that modern off of usage is still below its peak in 1910. The Corpus of Historical American English has a slightly different picture, with more-or-less stable usage from 1900 to the 1980s, and then a jolt up in the 90s and 2000s. Maybe it’s spreading, maybe not. But let’s talk about why it’s not bad either way.
I’ll start with the easiest objections. No, it shouldn’t just be from. Consider:
(1a) The numbers station is broadcasting from a shed off of Route 395.
(1b) *The numbers station is broadcasting from a shed from Route 395.
And yes, you can put two prepositions next to each other, as in this unobjectionable example:
(2) I pulled a coat out of the closet.
Going on to a somewhat more complex objection, antonymic phrases do not have to share structures or prepositions. The fact that you get on and not on of a train doesn’t mean that you have to get off and not off of it. Consider:
(3a) I put the sandwiches into the picnic basket, but someone has pulled them out of it.
(3b) One velociraptor was in front of Muldoon, the other next to him.
And now on to the involved discussions. One question is whether off is always sufficient, and off of thus always unnecessarily wordy. And the answer, I think, depends on that of a second question: whether off of is dialectal.
In my idiolect, off of is perfectly standard. I was probably in my twenties before I heard someone object to it. That’s not to say I can’t use off without of. To the contrary, I prefer (4) without of, though both forms are acceptable to me:
(4) The leaves fell off the tree.
That said, of is not always superfluous to me. A few examples where I find removing of to make the sentence noticeably worse:
(5a) It’s a way of profiting off of something you expect to drop in value.
(5b) My new invention will knock the socks off of the scientific community.
(5c) I broke your statue by knocking the top off of it.
You may not agree, even if you come from an off of idiolect, that these forms are better, but that’s not important. The key point is only that sometimes, to some people, off of is distinctly more mellifluous than off. Dismissing off of out of hand as superfluous is valid only in dialects that already don’t allow it.
Let me elaborate this “necessity depends on dialect” point by proposing an insane argument. I’ve mentioned before that, being from Pittsburgh, I am perfectly content to say The car needs washed instead of The car needs to be washed. Within my dialect, to be is often superfluous, and there are some sentences that I find greatly improved by omitting it. Thus, I could see arguing that to be is, at least sometimes, unnecessary. But if I argued this to someone speaking a “standard” dialect of English, I would sound crazy. Saying that of in off of is across-the-board unnecessary sounds equally crazy to me.**
So is off of dialectal and/or informal? The answer would seem to be yes to both. The Oxford English Dictionary calls it “only colloq. (nonstandard) and regional” in current use. The Merriam-Webster Dictionary of English Usage says it’s “primarily a form used in speech”. The Columbia Guide to Standard American English says it’s avoided at “Planned and Oratorical levels and in Semiformal and Formal writing.”
Those sources are generally pretty trustworthy with their opinions, and given the amount of people who find off of unacceptable, I’m inclined to believe that it really is dialectal. When that’s coupled with its primarily spoken usage patterns, it’s no surprise that it would feel informal, especially to people from other dialects. And using the Corpus of Contemporary American English as a measuring stick of informality, off of occurs in speech twice as often as in written fiction, about four times as often as in newspapers/magazines, and almost ten times as often as in academic writing. The more formal the style, the less likely you’ll see off of.
All that said, its informality doesn’t mean it’s an illiteracy. Off of used to be standard in English; the MWDEU starts off with a Shakespearean usage  and continues with Pepys  and Bunyan . In the last century, they show it used by Hemingway, Faulkner, and Harry Truman, among others. So if it is making a comeback, it’s no harbinger of linguistic doom, just a return to form.
Summary: There is nothing linguistically or grammatically wrong with off of. It’s nonstandard in some dialects and informal in most, so you should probably avoid it if you’re concerned about your writing seeming formal. But when formality isn’t a concern, use it as you see fit.
*: This is a surprising stance, because it comes from Patricia O’Conner of Grammarphobia, who’s normally a lot less judgmental about such things. In fact, three years later, she softened her stance, although she remains against off of. I included her original opinion because her reconsideration shows that even hard-line opinions can (and should) be altered in the face of evidence, so long as the commentator is reasonable.
**: In fact, I and others within my dialect seem to have strong intuitions about times when the to be can and can’t be felicitiously dropped, in the same way as I see off of. It’s not a matter of necessity but of felicity.