Prepositions of TIME 👉 IN / ON / AT / BY 👈 Common English Grammar Mistakes

Lesson Overview

English prepositions: These tiny words are so important! But they can be a little confusing at times too, right?

In this video, I explain how to use them when giving information about TIME.

Video Transcript

Hello! This is Emma from mmmEnglish, back with another lesson on the mmmEnglish YouTube channel.

Now a few weeks ago I made a video lesson using articles in English. If you missed it, you can watch it up here. But in that video, I said that articles are one of the biggest problems for English students because they are the cause of so many grammar mistakes!

And it’s true! As a University English teacher, I saw these mistakes all the time!

But coming very close behind mistakes with articles are mistakes with prepositions. Now, prepositions are words like these:

  • In
  • On
  • At
  • By
  • With
  • For
  • Over
  • Under
  • Of
  • To

There are many of them in English and like articles, prepositions are difficult to understand. Sometimes the reasons why you should choose one over another, it’s not really obvious. And sometimes there are exceptions and differences depending on who you actually talk to – whether they speak American English or British English.

So what’s the secret to these prepositions?

How can you possibly know when and how to use them properly?

Well, the answer might not be one that you like. There’s no simple rule, there’s no one answer.

Prepositions need to be learnt in context with the other words that they’re used with. Trying to understand why we say “in the car” and “on the bus” will only end in tears and frustrations!

By learning the phrase “in the car” together, all together, will make it easier to remember it and also to get it right every time. You’re not thinking about which preposition but you’re remembering the phrase. All of the words together.

Now last week I talked about these prepositions: in, on, at and by. But all when they’re used to talk about place or the position of something.

  • Let’s meet at the library.
  • He’s in the kitchen.
  • I’ll see you on the bus.
  • He’s waiting by the car.

If you missed that lesson, you can catch it up here.

But today we’re going to focus on these same prepositions but for when they give information about time.

  • I’ll be there in five minutes.
  • I’ll meet you at 3pm on Thursday.
  • We need to be there by noon.

So first, let’s go over the main points that we need to remember.

“At” is used in reference to specific times on the clock or points of time in the day.

“In” usually refers to period of time.

And “on” is used with dates and named days of the week.

And “by” is used specifically with an end point of time and it means no later than.


Let’s start with “at”. Use “at” for very specific times. Clock times for example.

  • The train arrives at 3:30.
  • The party starts at midnight.
  • The meeting will finish at 5:30.
  • I’ll be there at noon or at midday / at dawn / at dusk.

All of these words refer to specific time but we can also use “at” with other specific times of the day, like:

  • He doesn’t like driving at night.
  • I’m going shopping at lunchtime.
  • I read my daughter a story at bedtime.
  • Let’s talk about it at dinner (time) tonight. 

So there, I just called the time dinner. It’s not the meal name there, I’m using the time.

  • We’ll talk about it at dinner time, tonight. (But often it’s not spoken)

One thing that you must be careful about is with morning, afternoon, evening and night.

We say “at night” but for all of these other times of the day we say:

  • in the morning
  • in the afternoon
  • in the evening

And don’t forget the article as well, right?

Now there’s also some really common fixed expressions that use the preposition “at” – when you’re referring to a specific point in time.

  • She’s working at the moment.

So when you’re talking about an action that is happening around the present moment, you’re not using “in the moment” – all the Italians out there!

  • In the moment, I’m working on a very interesting project. NO!

It’s “at the moment”.

  • At the moment, I’m working on a very interesting project.
  • She’s a little busy at present, can I get her to call you back? 

It’s quite formal but “at present” means at this time.

  • I finish the course at the end of April.

So “at the end of” or “at the start of” a period of time is also a common way to refer to a specific point in time.

Note that if you say something happened in the middle of a period of time, you need to use the preposition “in”. But I’ll talk more about that in a moment.

  • We arrived at the same time.

So we use “at the same time” to say that two separate actions happened simultaneously – at one time.


Okay let’s talk about the preposition “in”. “In” is used for periods of time, so seasons or months or even longer periods of time like centuries or decades or years.

  • I was born in 1986.
  • He’ll visit them in October.
  • The ski resort is closed in summer.
  • He grew up in the seventies. That’s the period of time between 1970 and 1980.
  • It happened in the 16th century.
  • Don’t worry, it all happened in the past.

Just as we use “in” for periods of time we also use it for periods of time during the day when we’re not being specific. So…

  • They’re leaving in the evening.
  • The baby sleeps in the afternoon.
  • I work most productively in the morning.

But compare this to:

  • I start work at 9am.

So there’s specific time and there’s kind of general time. We can also use “in” to describe the amount of time needed to do something. So again, we’re talking about a period of time. A period of time.

  • They managed to complete the job in two weeks.
  • You can drive around the island in a day.

We can also use “in” to explain when something will happen in the future.

  • I’ll be ready in five minutes.
  • He’s gone away but he’ll be back in a couple of days.
  • You can collect your parcel in a week.

Now remember I told you earlier that if you’re using the expression at the end of or at the start of something you need to use the preposition “at”.

  • At the start of July.
  • Return it to me at the end of the day.

But, if you’re referring to the middle of a period of time your preposition needs to be “in”, “in the middle”.

  • In the middle of June.
  • It’s too hot to go out in the middle of the day.

Okay, here’s another really common fixed expression. “In time” – You’ll hear it all the time!

  • We made it in time.
  • Luckily, we arrived just in time.

This means that you weren’t late or you arrived just before the event started.

Don’t confuse this with “on time” which is another fixed expression.

  • Please arrive on time.

This means at the starting time, not later. If you’re told to arrive on time, don’t be late!

  • The teacher told them to arrive on time.
  • And even though they slept in, they arrived just in time!


Now let’s explore more about this preposition now. In English we can use this preposition for specific descriptions of time. Most commonly with days of the week and parts of the week.

  • She’s working on Monday. 

That’s a specific and a unique time.

  • She usually works on Mondays. 

By using the plural form there, I’m suggesting that this is a regular event. It happens every week.

  • We’re going to the theatre on Wednesday evening.
  • Let’s have a coffee on Friday morning.
  • It’s his birthday on Saturday.

So note that in spoken English “on” is often omitted in context like this:

  • She’s working Monday.

So don’t be confused if suddenly when someone says a sentence like this you can’t hear the preposition. In spoken English, it’s often dropped.

“On” is also used with dates.

  • The interview is on the 29th of April.
  • He was born on February 14th.

It’s also used with special days.

  • She was born on Valentine’s Day.
  • We’re moving house on Christmas Eve.
  • I have an exam on my birthday.

But here’s another little exception that you need to keep in mind. When you’re talking about festivals and about special periods of time, you can use “at”.

  • Are you going home at Christmas?

So that’s talking about the time around Christmas.

If you’re referring to the specific day, you need to use “on”.

  • On Christmas Day.
  • On New Year’s Eve.
  • What are you doing on New Year’s Day?
  • What are you doing at New Year’s?

Now this question is more general, you’re referring to the period of time around this holiday – usually there is a few days where everyone’s not working and they’re relaxing and hanging out so “on Year’s Day” means specifically that day.

But if you say “at New Year’s” you just mean the time around that day.

Another fixed expression that can be a little bit confusing is “at/on the weekend”

What are you doing on the weekend? is more common in American English.

What are you doing at the weekend? is more common in British English.

But either way, you’ll be understood. Both of them mean the same thing. But it’s good to know that there are two different ways to express this.


And lastly, “by”. Our last little preposition is very useful to give information about time. You can use “by” with the end time of an activity.

  • The show should be finished by 9pm.

It means no later than. So when it’s used with a specific time, it can mean on or before that time.

  • Please return these books by Friday.

That means no later than Friday.

So let’s recap. Let’s go over everything that we learnt in this lesson because it was a lot to take in!

  • “At” is generally used in reference to specific times on the clock or points of time in the day.
  • “In” generally refers to longer periods of time.
  • “On” is used with dates and named days.
  • “By” is used with times and named days of the week, but specifically, telling us an end time.

Well that’s it for this lesson! I hope that it’s been good revision for you to remind yourself about the correct way to use these really common English prepositions that give more information about time.

Now if you’ve got any questions at all, put them in the comments below and I will try to answer them as soon as I can.

If you really love the mmmEnglish Channel and you enjoy my lessons, then please make sure you subscribe just here or here. And check out some of the other lessons that I’ve prepared. This playlist here is full of grammar videos and this one here will help you to practise your speaking skills.

Thanks for watching and I will see you in the next lesson. Bye for now!

Links mentioned in the video

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