'On Friday' or 'In Friday': Which is Correct?

By
Carly Forsaith,
updated on
October 1, 2022

Are you wondering whether to say ‘on Friday’ or ‘in Friday’? It’s a valid question, considering prepositions can be tricky business. There aren’t specific rules for when you should use which one.

But this article will help you decipher one preposition from another and give you guidelines that can help you know which one to use.

But for now, the quick answer to your question is:

‘On’ is the correct preposition to use when saying ‘on Friday.’

‘In Friday’ is incorrect.

Prepositions

Prepositions help give more information about a noun or noun phrase. Although they do not, as mentioned, do not follow strict rules, some classifications can help you know which one to use.

For the purposes of this article, we will focus on ‘on,’ ‘in,’ and ‘at’ because those are most commonly confused. For example with 'on Friday' vs. 'in Friday', or 'interested in' vs. 'interested on.'

These prepositions usually describe time and place.

Prepositions of Time

Prepositions of time give information about when an event is taking place. Let’s look at the role of ‘on,’ ‘in,’ and ‘at’ when it comes to doing that.

  • On - primarily used for specific days/dates or part of a particular day or date
  • In - primarily used for periods of time
  • At - primarily used for a specific time

Here are some examples of how to use these prepositions of time in a sentence:

  • I’m having family over on Christmas Day.
  • Don’t you feel energetic in the Summer?
  • He always needs a book read to him at bedtime.

As mentioned, the categories outlined above aren’t a perfect science. For example, you can also you ‘at’ to talk about a period of time, like in the following sentence:

Shall we go hiking at the weekend?

Of course, these aren’t the only prepositions of time. Here are some others you might see around:

  • Since
  • For
  • By
  • Before
  • Ago

Here are some examples of those being used in a sentence:

  • They’ve been close friends since high school.
  • I’ve been coming here for years.
  • She’ll be long gone by then.
  • We have to get there before she leaves.
  • It wasn’t so long ago I was changing your diapers.

Prepositions of Place

Prepositions of place can supply more information about where something or someone is located.

Once again, ‘on,’ ‘in,’ and ‘at’ can all be used in this context. Here’s how:

  • On - mainly used to describe being positioned upon a surface
  • In - mainly used to describe the inside of a place
  • At - in an establishment or other contained location

Here are some examples:

  • If you’re looking for your keys, they’re on the table.
  • What are you doing in the pool? It’s cold!
  • They’re at the theatre.

These aren’t the only prepositions of place. Here are some others you might see around:

  • Nearby
  • Around
  • Next to
  • Behind
  • In front of

Here are some examples of those being used in a sentence:

  • She lives nearby.
  • I haven’t seen him around for a while.
  • Sit next to me!
  • He’s hiding behind the counter, can’t you see him?
  • You won’t be able to see anything with that massive post in front of you.

So Which One Is It, ‘On Friday’ or ‘In Friday’?

Of course, the correct way to say it is ‘On Friday’. Here are some example sentences:

  • What are you doing on Friday? We should hang out!
  • The delivery is expected to arrive on Friday evening.
  • On Friday, I’ll be long gone!

Can You Skip the Preposition?

You might be surprised to know that, in this instance, you can skip the preposition altogether and simply say ‘Friday.’ For example:

I’m sorry, but I don’t have time today; let’s meet Friday.

This is more colloquial language and isn’t recommended in formal situations or usual writing - unless it’s in a text or other message to a friend.

Concluding Thoughts on ‘On Friday’ vs. ‘In Friday’

So how are you supposed to remember? Beyond the generalizations outlined above, I recommend a lot of reading and watching - as much as possible. The more you expose yourself to high-quality English, the more your usage of prepositions will become natural.

For now, just remember that it is ‘on Friday’ and never ‘in Friday.’ You can also check out our other confusing words articles here.

Written By:
Carly Forsaith
Carly Forsaith is one of the lead freelance writers for WritingTips.org. Carly is a copywriter who has been writing about the English language for over 3 years. Before that, she was a teacher in Thailand, helping people learn English as a second language. She is a total grammar nerd and spends her time spotting language errors on signs and on the internet.

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