I sometimes see cases where off is followed by of, and it sounds awkward to me. For example, I would prefer

This story is based on a true story.


This story is based off of a true story.

What do native speakers think/prefer? Should I avoid that kind of usage?

12 Answers 12


The former is certainly preferable in UK English, formal or otherwise, whereas the latter is a style usually heard in conversational American English.

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    I’m pretty sure there are some UK dialects in which “off of” is common in conversational use. But agreed that the informality of it is probably more strongly marked in BrE than AmE. – PLL Mar 4 '11 at 16:16
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    I don't think it's even a dialectical affectation in the UK; if it's used here it's usually done for the purposes of irony (or ignorance at best). – lotsoffreetime Mar 4 '11 at 20:17
  • It is used in the UK -- I have a feeling it's dialectal too, though I've not seen an actual study. – Neil Coffey Mar 4 '11 at 21:36
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    It's used colloquially in the UK only recently (within last 5-8 years?). Scott Mills uses it constantly (digitalspy.co.uk/forums/showthread.php?t=182860) when saying where people are from, but it seems as if he's making fun of the phrase because he emphasizes and overuses it. It certainly didn't sound natural to the British ear at one time. I first heard Stephen Wright (US comic, not UK DJ) use it saying he washed mud off of mud, decades ago, it sounded really strange, but it seems to be creeping in to popularity nowadays. – Lee Kowalkowski Mar 4 '11 at 22:16
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    @Lee: I disagree strongly. I heard "off of" often in my youth (North London, 1960's). Not "based off of" though. – Colin Fine Apr 1 '11 at 10:38

I checked in the Corpus of Contemporary American English and there are only 7 instances when based off of is used, limited to spoken style. On the other hand, based on occurs with very high frequency in all sorts of discourse, particularly academic but also spoken.


You can’t base anything off of anything. Something is always based on something else.


Entire contents of that link:

"You can build a structure around a center, but bases go on the bottom of things, so you can’t base something around something else. Similarly, you can build something off of a starting point, but you can’t base anything off of anything. Something is always based on something else."

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    Good reference. +1 – Mehper C. Palavuzlar Apr 1 '11 at 6:56
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    This kind of rationalization doesn't actually tell us what people usually use. – herisson Feb 25 '17 at 5:45
  • "You can’t base anything off of anything." Ships can be based off of a particular region of coast. But that's a different meaning. Ships certainly aren't based on the coast. Well, with great creativity, you could come up with a story about a ship that was based on a coast. I'm not feeling that creative. – Mars Nov 28 '17 at 2:09

Some may wonder, how can these be synonymous, if "off" and "on" have the opposite meaning?

The key word in the Wiktionary link is nonstandard, which can be loosely translated as: yes, you'll hear it, but yes, there's a better way to say it.

Also, some prepositions in such phrases are incidental, and can fluctuate. You might say:

This movie was based on a true story.

This movie was based upon a true story.

This movie was based off of a true story.

All would have the same meaning, although the third has an amateurish ring to it.

  • Sorry but what is the meaning of 'amateurish ring'? – Johnny Lim Mar 21 '12 at 5:04
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    "Ring" refers to how it sounds. Based off of sounds rather amateur - i.e. informal, nonstandard, conversational, careless - not quite uneducated or illiterate, but a step toward that direction. In the U.S., it's not uncommon to hear it. If you tried to correct someone on it, they'd probably agree that based on was more proper, but they'd also likely regard you as nitpicky for pointing it out. – J.R. Mar 21 '12 at 10:01
  • The Wiktionary definition no longer labels the usage "nonstandard" anymore, as of today. – Fang Jing Dec 20 '16 at 20:54

Based on is the regular combination according to convention. Based off of is rather informal but also frequent. In academic papers I'd stick to based on.


It's very much a recent, emerging usage... enter image description here ...but looking at a selection of the written instances there, I see no obvious reason to assume the writers are all linguistically incompetent. The same pattern arises with the even more common based out of, covered by this earlier question. In neither case does it seem irrefutable to me that such usage is either grammatically or logically invalid.

It just looks "odd" to older people because statistically speaking they won't have heard these constructions so often as what they consider the "correct" versions, and when they do hear it, it'll often be from younger people who they assume are grammatically ignorant anyway.

I would advise OP that if he wants to avoid anyone thinking he's illiterate, he should avoid such constructions. But not everyone will think he's illiterate if he does decide to use them.

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    (to "Community Editor") I stand by my words as written. I see no reason to enclose "statistically speaking" in commas, I'm happy with the construction "not so often as what you think is correct", and you are one of those people who I think are living in some grammatical time-warp! – FumbleFingers Mar 21 '12 at 3:55
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    But compared to based on and based upon, based off of and based out of have near-zero usage. books.google.com/ngrams/… – 416E64726577 Apr 21 '15 at 19:37
  • Thank you for your helpful answer! The sentence "In neither case does it seem irrefutable to me that such usage is either grammatically or logically invalid" has a lot of negatives... and is hard for me to understand. – Fang Jing Dec 20 '16 at 20:58

Off what would such a clumsy expression be based? (I agree with Brian that one cannot "base off" of anything.) Here's ONE American who, while acknowledging that "based off" and "based off of" can be heard in illiterate spoken American English, does not support it.


Generally speaking, it's better to avoid wordy ways of stating the same thing. So in this instance, "based on a true story" is more correct even if it is the same meaning as "based off of a true story."

Really the only time when "based off of" is used is when it replaces "serves as a basis for" since "based on" provides essentially all the same meaning except for that. Though it's more like a guideline than a rule, and if you used one other than the other, most people would likely not even notice.


"Off of" is used in various forms of English (UK as well as US) where standard dialects have "from" or "off".

But I have never heard "based off of", "based off" or "based from": in my experience the phrase is only "based on".


Never heard it in Australia. To my ear its an obvious Americanism, and clumsy too. I would avoid it if you are trying to reach an international audience.


"Based on" is standard and traditional". "Based off of" is a new usage, until recently only used by children. I don't know how a locution becomes standard among children when adults have never heard of it, unless it came from a cartoon show on TV or something like that.


User 6769 has verified my following answer to a similar question:

I find the "based out of" and "based out of" usages to be faulty, indicating a misunderstanding of the word "based." "Based in" or "based on" are terms which, I believe, make sense considering the meaning of "based." "Based out of" and "based off of" can, of course, be explained as to what the user wants them to mean, but whether the user has made a good word choice is another matter.

As I understand the language, work and/workers can "come out of" the entity in which they are based, but they are not "based out of" there. Ideas can come from or off of a concept, in which case they are "based on" that initial concept, not "based off of" it.

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