# “One-to-one” vs. “one-on-one”

I said: "Tomorrow will be our one-to-one meeting with Mr.XYZ."

My friend: "OK, one-on-one."

Which is correct?

One-to-one

Or

One-on-one

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I'm not sure'our one-[]-one meeting' would be strictly correct either way. – TimLymington Aug 20 '12 at 15:37
What @Tim said. You can't meaningfully speak of our one-on/to-one meeting with A.N. Other, since that would imply at least three people in the meeting (the speaker, listener, and the other person). – FumbleFingers Oct 22 '12 at 15:27

One-to-one is used when you talk about transfer or communications. You may use one-to-one when you can identify a source and a destination. For eg., a one-to-one email is one sent from a single person to another, i.e., no ccs or bccs. In maths, a one-to-one mapping maps one element of a set to a unique element in a target set.

One-on-one is the correct adjective in your example. See Free dictionary. One-on-one is used when there are two people involved in mutual exchange, as happens in a meeting.

The difference is rather usage-based, but most important: Do not forget the hyphens.

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One-to-one is also a computer science term defining a relationship between two tables in a database in which one record corresponds to exactly one record in the other table and vice versa. – Neil Apr 19 '12 at 14:09
@Neil That's analogous to his Maths comment - about set mappings. – d'alar'cop Feb 14 '14 at 9:48
@d'alar'cop Math is hardly the same thing as computer science. – Neil Feb 14 '14 at 9:54

This might be confusing because of the similar phrases such as "man-to-man" and "heart-to-heart", which refer to an interaction, vs one-to-one, which refers to a transaction (or in the database world, a relationship).

Meanwhile "One-on-One" has a sort of domination/subordination sound to it, where one is on top of the other.

At the end of the day, when two people are having a private conversation or face off or meeting, it's a one-on-one.

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Where is the "domination sound" when you talk of a one-to-one email communication? – Bravo Apr 19 '12 at 6:14
@Shyam -- I said there was a domination sound to "one-on-one", because it sounds like someone is on top of the other or above the other. one-to-one sound more appropriate, I think, it just has another connotation it's not available. – Anthony Apr 19 '12 at 6:22
Rather than a domination/subordination connotation, I would've said it's more of a competition connotation (it may well be a friendly competition), but that may be a regional thing or it may just be that that's simply the context in which I've heard "one-on-one" used more. So for "face-off" I'd use one-on-one, but for meeting, I'd use "one-to-one" (unless maybe there's a contest of wills involved...), or "face-to-face". By the way, I was almost tempted to downvote for using the phrase "at the end of the day", but that wouldn't have been fair ;-) – Amos M. Carpenter Apr 19 '12 at 6:34
@aaamos Face-to-face is another great example of why "one-to-one" would be more correct but just isn't available. Maybe we can agree that one-on-one has a "zero-sum" connotation, where only one of the two can be "on" the other? – Anthony Apr 19 '12 at 6:47
@Aaamos, I do think one on one has a competitive connotation. (One on one is widely used in basketball to mean two players who challenge each other.) I would call a meeting in a business setting a face-to-face meeting rather than a one-to-one or one-on-one meeting. – JLG Apr 19 '12 at 13:04

Either may be correct, so the tie-breaker is local usage and avoidance of confusion. In my circle, one-to-one connotes a mathematical relationship while one-on-one is used more often in athletic contests. So a meeting might be either. But if you talk about a meeting as one-to-one, the listener may think you are referring to the hour.

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I can't see in what way the mathematical relationship is appropriate for a meeting. Could you explain that? – Em1 Oct 22 '12 at 14:01

Face-to-face can also imply there are more than two participants. One-on-one has been used in business meetings for years; and, yes--there is often a "dominance" factor. One is a "leader" or "manager" and one is a subordinate. It's not necessarily pretty, but that's business for you.

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One-to-one is less combative, and implies a communication between two people.

One-on-one implies an interaction between two people, and can carry more of a combative subtext, like a one-on-one karate fight.

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Adding point to accepted answer. one-on-one / person-to-person meeting: 1) One person listens to other to know his ideas, suggestions, feedback. One person tries to understand the other persons' expectations, problems and suggestions. One of purposes of this one-on-one meeting would be, each person would like to improve the quality of delivery/contribution to the organization/purpose/business.

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