Tell me please if I need to use check or check on in the following context.

I am not sure if the facts he cited are true, so I had better check/check on them.

If both are correct there, then what is the difference?

  • 1
    I would use check in this instance. Check on someone or something means to look at them to make sure they are OK, or to monitor their progress - but it can also be used in the sense of 'make sure something is accurate', so it wouldn't be wrong in your sentence. Commented Nov 25, 2019 at 9:00
  • I think the use of "had" there is incorrect. You are saying that you are not sure of something now which means you haven't checked the facts yet.
    – AIQ
    Commented Nov 25, 2019 at 9:32
  • 2
    'Had' is correct. 'I had better [do something]' means 'I should [do something]', or 'I would be wise or sensible to [do something]'. To say 'I better [do something]' instead is informal, conversational, or dialect. Commented Nov 25, 2019 at 9:36
  • 1
    Possible duplicate of "Check" or "check out" or "check on"? Commented Nov 25, 2019 at 14:04
  • Note that to check out is a true "transitive phrasal verb", so an object pronoun can be spliced in as ...so I'd better check them out. But you can't do that with ...so I'd better check them up (invalid). That would require the object to be placed after the verb with a preposition, as in ...so I'd better check up on them. Commented Nov 25, 2019 at 14:10

1 Answer 1


Check on X means make sure X is OK.

Check X means to get the current state of X, but you typically wouldn't do something unless X is doing something wrong. Because of that implication it's often interchangeable with check on.

Check on X is probably a bit more typically used if X is some distance from you or some time will pass before you actually check.

Check on the food in an hour.

Check the food now.

but switching these around isn't incorrect and doesn't sound strange.

In the sense of going to someone's house and making sure someone is OK, you'd almost always use check on and not check. Not using on in the following sentences sounds a bit like you mean "check" in the sense of "medically examine":

Check on Margaret when you get into town.

Check on my cat when you get home.

Facts are not people, so you'd say check and not check on.

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