We can use the prepositions “in” and “on” in similar ways when talking about times and dates. However, they are not interchangeable, and it would help to understand which is correct of “in the week” and “on the week.” This article will help you with that answer.
Is It “In The Week” Or “On The Week”?
“In the week” is correct when referring to an unspecific time period. While the “week” is specified, the exact time or day when the thing will occur is not, which is why “in” works. We only use “on the week” when we know the exact “week” when something might happen.
“In” is the general preposition we use for most time-based events. The idea behind it comes from being able to establish an unspecified period of time, and we might do so as follows:
- In the week, I’m going to need your help on this.
- I will hand this project to you in the week.
We can promise that something will happen within the week that we mentioned when using “in the week,” but we can’t guarantee the time or day we do it.
Of the two prepositions, “on” is the more specific one. We only use it to refer to something we can guarantee will happen at a particular time.
- On the week of the 14th, I need you in the office.
- You should be away on the week of the 8th, right?
As you can see, “on the week” has to specify when the week starts. We use “on” to refer to specific times, so without being more specific about the start of the week, it is never correct.
Is It “In The Last Week” Or “On The Last Week”?
We might also be interested in learning about different tenses. What happens when we start to think about “last week?”
“In the last week” shows that something happened at a general point in the last week. There is no way to confirm when that time happened, but we use “the” to at least specify the correct week (as in the last seven days). “On the last week” only works for specific time frames.
“In the last week” works like this:
- In the last week, I have made four sales.
- You have let me down too many times in the last week!
We use “in” to refer to an unspecific time during the last week. It might also mean that an event or situation happened so many times that we can’t narrow it down.
We use “the” to specify that we mean the last week that just passed. “The” helps us to establish a little bit of specificity, showing that we mean the last seven days.
“On the last week” is incorrect in most cases. We can only use it to refer to specific time frames, like so:
- On the last week of the month, I will be paid.
- He was not here on the last week of work.
As you can see, we have to include “on the last week of” something to specify what we mean.
Is It “In This Week” Or “On This Week”?
“In this week” means that we expect something to happen in the coming week, though we’re not entirely certain when it will occur. “On this week” establishes a bit more of a guarantee, where we know something will happen or has happened before.
Generally, “this week” doesn’t come with any prepositions. The prepositions are often implied, meaning that “this week” is usually the most suitable choice:
- This week, I need you to sort out this list of chores for me.
- This week, I won’t be here to help you.
However, we can use the prepositions in certain cases. Here are a few examples to show you what we mean about this:
- In this week, I expect you to have figured out this project.
- On this week, three years ago, my grandfather passed away.
“In this week” is a general statement to show that we expect something to happen during the course of the following week.
“On this week” is more specific, and we mostly use it to refer to a specific week that was repeated a few years ago. It’s best used when reminiscing or thinking back to when something might have happened to you.
Is It “In Weekdays” Or “On Weekdays”?
“In weekdays” is always incorrect. “In” is not the right preposition to use with “weekdays” because we are no longer referring to unspecified times. Since “weekdays” is specific, we can only use “on weekdays” to refer to them.
There are no exceptions or edge cases for this rule either. “Weekdays” are always specified (the days from Monday to Friday). Therefore, only the specific preposition “on” is correct when using it.
- Correct: I need your help on weekdays if you’re happy to offer it.
- Incorrect: In weekdays, I need you to be in the office more often.
- Correct: On weekdays, I expect my deliveries to get here before I head out!
- Incorrect: We aren’t in there in weekdays because there are plenty of better things for us to be doing.
Which Other Prepositions Can Be Used Before “The Week”?
There are a couple of other prepositions we might want to use with “the week” that aren’t “on” or “in.”
During The Week
“During the week” means that we expect something to happen at some point in time during the course of a week. It’s synonymous with “in,” where we know it will happen this week, but we’re not sure of the exact time or date.
- I need you to be here during the week.
- During the week, I expected multiple emails from him.
By The Week
“By the week” means we are setting a specific deadline of a “week.” We usually announce which “week” we mean when using “by” so that everyone understands the intended deadline.
- By the week of the 14th, all new procedures should be in place.
- I expect this project by the week of the 19th and no later!
Martin holds a Master’s degree in Finance and International Business. He has six years of experience in professional communication with clients, executives, and colleagues. Furthermore, he has teaching experience from Aarhus University. Martin has been featured as an expert in communication and teaching on Forbes and Shopify. Read more about Martin here.