When to use “on” and when to use “in”

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Nate asks: What are the proper usages of the words “in” and “on” in a sentence? I often confuse the two. Here are some examples: “The boat is in/on the water,” “We are in/on the planet,” “We’re going to the concert in/on July 1st.”

The use of prepositions in English is frequently idiomatic. General guidelines exist, but be prepared to learn individual expressions in which the preposition does not adhere to the guidelines.

In the case of the prepositions in and on, here are the most usual uses.


in mainly denotes “rest at”:

PLACE: He lives in the country. He lives in Chicago. (BUT, He lives at 2300 Wabash Ave.)
TIME: I’ll be there in an hour.
MANNER: The child ran down the steps in tears.
REFERENCE: In my opinion we need a referendum. They are happy in their marriage.


on indicates proximity and position above or outside:

PLACE: He sat on the fence.
TIME: He was not thinking well on that occasion.
REFERENCE: He asked my opinion on the matter.
CONDITION: We’ll hire him on your recommendation.

The examples given in the question:

We are on the planet.
We are going to the concert on July 1.


We are going to the concert in July.

As for the example about the boat, either is correct, according to what is meant:

The boat is in the water. (As opposed to being on dry land for the winter)
The boat is on the water. (Look at all those boats out there on the water!)

However, it would be unidiomatic to say The ship is in the ocean or in the sea, unless you mean that it has sunk. The ship is on the sea.

Related to the question of when to use in is that of when to use into. While in denotes the state of being “at rest” in a place, or at least being (in a sense) surrounded by something, into denotes motion towards:

The dog jumped into the water.
The children (who were already in the water) jumped in the water.

When deciding whether to use in or into, ask yourself if the person or thing you are talking about is moving from one place to another. If so, use into.

More about prepositions in later posts. Stay tuned!

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139 thoughts on “When to use “on” and when to use “in””

  1. What is correct?

    “If you need me, I am in the back or I am at the back?”

    “If you need me, I am in the back of the garbage bin or I am at the back of the garbage bin?”

    “If you need me, I will be in the back or I will be at the back?”

    Thank you.

  2. REFERENCE: He asked my opinion on the matter.

    IMHO, I think this use is a stretch. I would substitute “about” for “on.”

    He asked my opinion about the matter.

    More and more it seems that writers have forgotten the word “about” and use “on” instead, a rather annoying tendency.

  3. hi!

    Please explain the difference of errands and chores..

    I really find this website very helpful for me especially that I am an english teacher here in the Philippines

  4. Errands: Getting things done out of the house. Going to the store, going to wash your car, etc. Doing something out of the house.

    Chores: Doing things in the house, like doing laundry, cooking, cleaning the bathroom, paying the bills, etc.

    Correct me if I’m wrong.

  5. We are going on vacation. We will go in the car, in the camper, in the truck.

    We will go on a plane, on a boat, on a train, on a bus.

    this doesn’t help:
    use in with bodies of water, use on with surfaces.
    nor this: in mainly denotes “rest at”
    on indicates proximity and position above or outside.

    I wonder if it’s because someone else is driving the plane, boat, train or bus. But the vacationer would be driving the car, camper, truck.


  6. The question above is possibly because we have to bend to get in a car ect..
    We can walk on a plane ect…

    That is what I was told anyway..
    Correct me if I am wrong.

    New to this site but willing to help if I can

  7. Mike, include more details. This is what I think is the correct usage:

    “If you need me, I am in the back”

    “If you need me, I am in the back of the garbage bin” (if you are inside the garbage bin, in the back of it)

    “If you need me, I will be in the back”

    Anybody please feel free to correct me, if needed.

  8. Thx a lot..!!! It was very helpful.
    But i am still confused with this sentence below. Reading above i understand both are correct. Correct me if i am wrong. Also please explain.

    Mike is working on billing module.
    Mike is working in billing module.

  9. I have a doubt. Should we say on October 2008 or in October 2008. I know we use in for months and years (in December, in 2009) but how about the two together. I speak English as a foreign language so I’m not that accurate in using prepositions. :S Thanks for your help

  10. I need your comment because I’m confused what to use “write your answer on the blank” or “write your answer in the blank”

  11. I love you all for your questions and comments ! Maybe I will finally stop thinking I’m a certified num skull, and that error is human. Please do you say your birthday has passed or past? Which one is right? You get a treat if you got it rigth or if you get it right?

  12. Tt,
    Your birthday has passed.
    Your birthday is past.

    Check it out:

    You get a treat if you get it right. (Spoken before the person takes the test.)
    You get a treat if you got it right. (Spoken after the person has taken the test, but before the test has been graded.)

  13. regarding the use of the word ‘in’ and ‘on’. from this two sentences: the nurse observes a nursing assistant providing care on the medical/surgical unit. can we use the word ‘in’ instead of ‘on’ here. how about this; a patient in the outpatient clinic prioritizes patients for evaluation. again can we use the word ‘on’ here. another sample: a patient suffers from a pulmonary embolism in the recovery room.
    how about the use of has been. the nurse notes that there has been no drainage since the client’s return..is ‘has been’ past tense or what?

  14. I am having a hard time here..trying to comprehend if it’s on june 2005 or in june 2005….but this site helped me a great deal ! Realized it should be in june 2005 and it’s on june 23, 2005 or june 3 (with the absence of year, use ON only if the month and date is present)….Thanx a bunch! God bless

  15. ADDITIONAL: There’s a rule of when to use ‘in/on’ when pertaining to what if vehicles are ‘public’ or not. But, I’m not sure if, if you are pertaining to a public vehicle, you would use ‘on’.

    Can someone solve this question?

  16. Thank you very much guys.
    You are awesome . I am from Turkey , all that staff is so useful for people who learn English . I like English grammar ,but i confuse prepositions sometimes.
    Thanks a lot.

  17. which is correct?

    I will assist my niece in her graduation day or I will assist my niece on her graduation day?

  18. Question: More detailed information is available ON appendix A? or More detailed information is available IN appendix A?

  19. hi… i find this site very helpful. here’s mine..

    do we say, “Your hair is in the air” or “Your hair is on the air” ?

    please explain why so? thanks!

    (my guess is it’s… “hair is on the air” ?

  20. RE:
    hi… i find this site very helpful. here’s mine..

    do we say, “Your hair is in the air” or “Your hair is on the air” ?

    please explain why so? thanks!

    (my guess is it’s… “hair is on the air” ?

    i think my guess is incorrect since it sounds odd. 🙁
    perhaps it’s “hair in the air”. i get really confused with these two prep. :-((

  21. Re the original post: You suggest “The ship is ON the sea” – seriously, or was that a typo? That sounds at least as weird as many of the other unidiomatic examples you are countering. In BrE, a ship is AT sea and if I’d heard “on the sea” in American literature or films, I’m sure I’d have remembered it.

    @Annette: The “rule” about not ending a sentence with a preoposition never was a real rule in English. It was true in Latin and some people therefore applied it to English as well. Sometimes it is ugly and confusing to end with a preposition and sometimes it’s the best way to express something. It’s style, not grammar.

  22. As a frequent observer of the space industry I get many confusing remarks from people in the USA, for example. They say “on orbit”, I say “in orbit”. Recently I saw an article from NASA titled An event was occurring “in July 7”. Some people in the USA say it my way, some say the other way. What is going ON here????

  23. Is it correct to say “…this request for travel appears in the approved budget plan…” or “…this request for travel appears on the approved budget plan…”

  24. @alex: To me, “budget plan” sounds provisional, but you say it’s “approved”, so I’d remove the redundancy and write either “in the approved budget” or “on the approved plan”.

  25. I am lost here. When a particular tribe/group wants to create a site, for eg: xyz in facebook or xyz on facebook? Please help me out. Many thanks.

  26. if IN means inside something.. why do we say “he was not on the train” instead of “he was not in the train” ?

  27. I will be able to talk to you Saturday
    I will be able to talk to you on Saturday

    Which on is correct?

  28. @Elissa: In British English, most people use “on”. However, I don’t think that is the case with AmE as I have heard many Americans omit it.

  29. I am still confused in using “IN” as a past tense when referring to days or months and “ON” as future tense when referring to days and months or even year.

    please reply.


  30. We are creating a brochure and would like to know whether to use in or on:

    Receive Fun Miles with every purchase made in the best island.


    Receive Fun Miles with every purchase made on the best island.

    Thanks for your advice!

  31. I am also confused in the use of ” IN” and ” “ON”. For example if we are writing a sentence ” The university is offering ph.D level research o Biology or IN biology?

  32. Examples for in/on/at:

    in: in the morning/in the afternoon/ in the evening/ in November (months)/ in summer(seasons)/ in 1992 (yrs).

    on: on Sundays/ on Montay (days of weeks)/ on May 4th (dates)/ on Sunday afternoon.

    at: at 8 o’clock/ at noon/ at midnight/ at Easter/ at Chrismas (occasions)

  33. What’s right:

    1. Would you like to be speaker A or B in the dialog?
    2. Would you like to be speaker A or B on the dialog?

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