The short version: “based off of” is slang. Use “based on” instead.
When I first started noticing the phrase “based off of” in student papers, I thought it was just a careless typo. But I’ve noticed it more and more in online writing and in casual speech. (UPDATE — by 2020, I see this phrase frequently in formal student papers.)
Like “yeet” or “awkward!!”, it’s popular with younger people, but it’s not used in formal academic contexts. I wouldn’t interrupt and correct a student who used “based off of” in a class discussion, but I would flag it as too informal for a research paper or analytical essay.
The phrase “based off of” may be related to “flying of off,” as it seems to mean something like “is now different from, but was once more obviously similar to.” By contrast, “based on” may be taking on the meaning “still directly connected to.”
The phrase “based on” means exactly what users of “based off of” think they are saying, but if a thing is “off of” something, it’s not on a base, so “based off of” makes no sense.
Because many of my own students who are training to be teachers use “based off of,” I suspect in another generation only the most linguistically conservative will bother to notice, much less correct, this usage. I shall, however, continue to flag it as incorrect.
When our homeschooled 12yo daughter started using it, my wife and I agreed to coordinate our efforts to crush it. But the other day when the girl wrote me a brief personal essay, she used “based off of.” And I see it more and more frequently in college essays.
Young people today encounter much more of the language of their peers than their parents did. As a kid near Washington D.C. during the 80s, I spoke to my friends one at a time on the telephone. One summer during middle school, while I was talking to a girl on the phone in my parents’ bedroom, she surprised me by saying “I love you,” and I remember at that precise moment my dad strolled past in his bathrobe, so during the time when I might have been expected to say “I love you, too,” my adolescent brain was busy wishing that I had one of those new-fangled cordless phones with a big antenna so I could have taken this call in my room. (For the record, I did *not* say “I love you, too.” The relationship didn’t last past that summer.)
After I finished grad school in Toronto and took my first faculty job in Wisconsin, I moved to southwestern Pennsylvania in 2003, where I encountered regionalisms like “That table needs washed” or the use of “anymore” to mean something like “nowadays.” Around the same time, I noticed the structure “by [participle], it can be…” as in “By thinking, the problem can be solved.” or “By following the U.S. Constitution, our rights can be protected.” That phrasing is, I believe, a natural first step when a student tries to move from writing a subjective “I” essay to a more objective, evidence-based essay, and my advice in such a case it to get the student to prefer the active voice (“Thinking solves problems” or “The U.S. Constitution protects our rights”).
The phrase “based off of” appears just once in Google’s database of books before 2000, while “based on” becomes steadily more frequent over that time span.
We expect the language in printed books to be more formal than everyday language, so the absence of “based off of” in the printed corpus suggests what I already know, that it’s an informal construction.
A Google search for “based on” and “based off of” told me what I expect. The internet is full of pages that are written by non-professionals without editors, so we would expect to find a greater percentage of informal language constructions online.
|“based on”||“based off of”|
The first row shows that for every 158 instances of “based on” that Google found in its entire database, there is one instance of “based off of.”
When I limited the search to the past year, it looks like the usage of “based off of” has increased — there is one per about 106 instances of “based on.”
I ran the search several times to make sure I wasn’t misreading the results, and while the actual numbers did fluctuate with each query, the basic proportions are the same. During the “past month” subset of its database, Google returns about 1.8 instances of “based on” for every instance of “based off of.”
However, when I limited the search even more to the past week, the past 24 hours, and the past hour, the trend doesn’t hold.
|“based on”||“based off of”|
If I had chosen to remove the “Past Week” row and the “Past 24h” row, I would have ended up with what looks like convincing evidence that “based off of” is crushing “based on” in the English language. Presumably those 38 million results that Google found within the last week should also be included in the results Google returns for the last month.
So, while I set out to track whether Google can tell me anything about the prevalence of “based on” vs “based off of” over time, I ended up finding evidence that Google’s Search Tools -> time restriction operations don’t seem to add up. I also found some data that doesn’t match my working hypothesis. I could have easily dropped out some of the data in order to make what looked like a more persuasive blog post, but the persuasion would only be superficial, as anyone could have done the search independently and come up with the missing data that would have destroyed such a weakly-supported claim.
I’ve learned that “based off of” is not a regionalism; that in Google’s database of printed books before 2000, the phrase appears only once in the 19th century, 21 times in the 20th century, and 17 times so far in the 21st century (including two journalistic instances in which the author is quoting ad-libbed speech, and once in the title of a self-published book written by a college student); and that of the sources that Google tagged in its databases as “Past hour” and “Past month,” the phrase “based off of” approaches parity with “based on.”
My daughter is a kinesthetic and auditory learner. As long as she has something to do with her hands, she’ll listen to an audiobook and absorb its contents pretty well. She has no trouble following the dialogue in a Shakespeare play, and she recently finished a three-week run playing Young Estella in a professional adaptation of Great Expectations (where the audition notice included the requirement that actors know an upper-class British dialect). She’s very well-spoken for someone her age, which means we really notice when she starts using language constructs from the tweeny-bopper subculture. When she gets excited about typical tween girl stuff, we noticed that she starts up-talking — including an invisible question mark at the end of a statement? Using a tone that invites the listener to offer a supportive “uh-huh”? Because the speaker is, like, going out on a limb? And wants affirmation? Or, when used by a speaker in a position of power, pretending to be less than certain, in order to get a listener to agree? To a statement? That’s really more like a demand? Without sounding imperative? So we’re all ready to go on now? Except for you?
My introverted teen son isn’t as talkative, and what he does say in his rumbling base (here he is singing “Old Man River” and “Be Prepared” from The Lion King) is usually pretty well thought out. Often he’s quoting facts or opinions that he’s recently read, but he repeats them with a question mark, which is his ritualistic way of inviting a conversation by asking, “What do you think about this?” He does quite a lot of reading, so he probably encounters more formal language in books than he does informal language from the mouths of his peers.
So, while I’m satisfied that up-talking is a culturally-determined request for affirmation, and the awkward passive constructions are a reasonable step towards more objective formal writing, I’m not aware of any cultural force that might explain why I suddenly started noticing “based off of.”
Had I searched for “based off” instead of “based off of,” what might I have found?
At any rate, while I find lots of evidence that the phrase is increasingly popular in many informal contexts, in the world of academic and professional writing, using the phrase “based off of” is, like a split infinitive, a red flag to the prescriptive grammarians.