# "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

• I'm not sure'our one-[]-one meeting' would be strictly correct either way. Aug 20, 2012 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). Oct 22, 2012 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.

• 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, 2012 at 14:09
• @Neil That's analogous to his Maths comment - about set mappings. Feb 14, 2014 at 9:48
• @d'alar'cop Math is hardly the same thing as computer science.
– Neil
Feb 14, 2014 at 9:54
• And one-on-one is a form of several sports where 2 people compete against each other. Feb 23 at 20:39
• @Neil: Relational databases are defined in terms of mathematical set theory, and usually that theory is presented in a CS course called "discrete mathematics". E.g., see Rosen, Discrete Mathematics and its Applications, Sec. 9.1 (mathematical relations), and Sec. 9.2 (relational databases). Feb 24 at 2:45

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.

• Where is the "domination sound" when you talk of a one-to-one email communication? Apr 19, 2012 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. Apr 19, 2012 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 ;-) Apr 19, 2012 at 6:34
• @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, 2012 at 13:04
• 'face-on-face' is just not an alternative. Aug 20, 2012 at 16:49

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.

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.

• I can't see in what way the mathematical relationship is appropriate for a meeting. Could you explain that?
– Em1
Oct 22, 2012 at 14:01

I would always prefer "one-to-one" as in a "one-to-one" meeting vs. "one-on-one," as I think better communicates a sense of interpersonal communication. My evidence? In basketball, you guard someone "one-on-one" not "one-to-one."
Also, we say "face-to-face" not "face-on-face" we say "heart-to-heart" not "heart-on-heart," "I spoke to him man-to-man." That last phrase means a conversation between two men where personal matters -- perhaps "difficult" ones -- were discussed.

My "credentials"? I've been a professional writer for 42 years -- first at major ad agencies, then marketing for leading int'l corporations (Visa, etc), last 6 years as a Sr UX writer at a 2500 employee financial firm. Also author of an academic book that's in the libraries of Harvard, Stanford, Oxford, Tokyo Univ., etc.

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.

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.