Preposition of Time: How to Use In, On, At and Exercises

Prepositions of time are used to show when an action, event, or situation happens. They are common in everyday English and are especially important when talking about dates, schedules, routines, deadlines, and periods of time.

Among the many prepositions used with time, in, on, and at are some of the most important for English learners. They are often confusing because each one is used with different types of time expressions. Other prepositions such as since, for, by, until, and during also help describe when something starts, continues, or ends.

This guide explains what a preposition of time is, how to use in, on, and at, how these prepositions differ when referring to time and place, common mistakes to avoid, and practical exercises to help you review the rules.

What Is a Preposition of Time?

A preposition of time is a word used before a time expression to show when something happens or how an action relates to a particular period.

Common prepositions of time include in, on, at, since, for, by, until, during, and from…to. Each preposition has a different function, so choosing the correct one depends largely on the type of time expression that follows.

For example, in is commonly used with months and years, on with days and dates, and at with specific times. Since identifies a starting point, for describes a duration, while by indicates a deadline.

Understanding these basic relationships makes it easier to use prepositions of time accurately in both writing and conversation.

In, on, and at are the three prepositions learners encounter most often when talking about time. Although there are some fixed expressions that need to be memorized, their main patterns are relatively easy to recognize.

A useful starting point is:

In → months, years, seasons, and longer periods
On → days and dates
At → specific times and certain fixed time expressions

These are general patterns rather than rules based only on how specific a time seems. The correct choice depends on the type of time expression that follows.

How to Use In

We generally use in with months, years, seasons, centuries, decades, and parts of the day.

Common patterns include:

• in + month

• in + year

• in + season

• in + century

• in + part of the day

For example: She was born in 2000.

Other common expressions include in January, in summer, and in the 21st century.

We also use in with the general parts of the day:

• in the morning

• in the afternoon

• in the evening

However, English normally uses at night when referring to nighttime in general. In the night is also possible when referring to a particular event or period during the night. For example, someone may say that a baby woke up in the night to describe a specific occurrence.

We can also use in to say when something will happen after a period of time:

The course will start in two weeks.

Here, in two weeks means two weeks from now.

For more examples of how in is used with months, seasons, years, and parts of the day, you can refer to the British Council explanation of prepositions of time.

How to Use On

We generally use on with days, dates, and specific days combined with parts of the day.

Common patterns include:

• on + day

• on + date

• on + day + part of the day

For example: We have an English class on Monday.

We can also say on July 10 or on Monday morning.

The distinction between in the morning and on Monday morning is important. In the morning refers to the morning in general, while on Monday morning refers to a particular morning.

The same pattern can be used with other parts of the day:

• on Tuesday afternoon

• on Friday evening

We also use on with particular special days, such as on Christmas Day, on New Year’s Day, or on my birthday.

When talking about weekends, there is a difference between British and American English. At the weekend is common in British English, while American English frequently uses on the weekend or on weekends. Both forms are standard within their respective varieties of English.

How to Use At

We use at with specific points in time, especially clock times.

For example: The meeting starts at 9 a.m.

Common expressions with at include:

• at 6 o’clock

• at noon

• at midnight

• at lunchtime

• at night

We also use at with some holidays or holiday periods:

• at Christmas

• at Easter

When referring to a specific day within a holiday period, however, on is normally used:

on Christmas Day

This distinction is similar to the difference between talking about a holiday period and a particular day.

The expression at night generally refers to nighttime as a whole or to nighttime in general. By contrast, in the night can refer to a particular event or period during the night.

In, On, and At: Quick Comparison

This table provides a useful overview, but learners should also remember common fixed expressions such as at night, at Christmas, and on Monday morning.

Preposition of Time and Place

The same words in, on, and at can be used for both time and place. However, their meanings depend on the context.

When referring to time, in commonly introduces broader periods, on introduces days and dates, and at introduces specific points in time. When referring to place, in commonly describes a position inside an area or space, on often refers to a surface, and at identifies a particular location or point.

For example, in 2025 refers to a year, while in London refers to a location. Similarly, on Monday refers to a day, while on the table describes a position on a surface.

This distinction is useful when studying preposition of time and place because the same preposition may have different functions depending on the context.

If you want to expand this topic, the British Council guide to prepositions of place provides further explanation of in, on, and at in location contexts.

Other Common Prepositions of Time

Besides in, on, and at, several other prepositions are commonly used to describe when something starts, continues, or ends.

Since and For

Since is used with a starting point in time, while for is used with a period or duration.

The basic patterns are:

• since + starting point

• for + duration

For example:

• She has lived here since 2020.

• She has lived here for four years.

The first sentence tells us when the situation began. The second tells us how long it has continued.

Common expressions with since include since Monday, since 2020, and since last year. Expressions with for include for two hours, for three weeks, and for several years.

By and Until

By and until can both refer to a future time, but they express different ideas.

By indicates a deadline. It means something should happen no later than a particular time.

Until indicates that an action or situation continues up to a particular time.

Compare:

• Please finish the report by Friday.

• I will stay here until Friday.

In the first sentence, Friday is the deadline for completing the report. In the second sentence, the situation continues until Friday.

This distinction is particularly useful when talking about schedules, work deadlines, appointments, and plans.

During

During shows that something happens within a particular period or event.

For example: He fell asleep during the movie.

The movie provides the period in which the action happened.

Unlike for, which focuses on duration, during focuses on the period or event in which something takes place.

Compare:

• She studied for two hours.

• She studied during the afternoon.

The first sentence focuses on how long she studied, while the second focuses on when the activity took place.

From…To

From…to is used to show the beginning and end of a period.

The basic structure is:

from + starting time + to + ending time

For example: The office is open from 8 a.m. to 5 p.m.

This structure is common when talking about working hours, class schedules, opening hours, and other fixed periods.

Common Mistakes With Prepositions of Time

Prepositions of time are short words, but using the wrong one can make a sentence grammatically incorrect or unnatural. The following mistakes are particularly common among English learners.

• Confusing In, On, and At

The most common mistake is choosing a preposition that does not match the time expression.

Remember the basic patterns:

• in July

• on Monday

• at 8 p.m

However, learners should also pay attention to fixed expressions. For example, we say at night, not normally “in night”, and on Monday morning, not “in Monday morning”.

The best approach is to learn the general patterns while also memorizing common combinations.

• Using Prepositions With Yesterday, Tomorrow, Last, Next, and Every

Sometimes expressions normally appear without in, on, or at.

These include expressions with words such as today, tomorrow, yesterday, this, every, next, and last.

For example:

• I will call you tomorrow.

• She visited us last week.

• We have a meeting next Monday.

• He goes jogging every morning.

We do not normally add on before “tomorrow” or in before “next Monday”. Cambridge also notes that at, on, and in are generally omitted before expressions beginning with words such as each, every, next, last, this, that, one, any, and all.

• Confusing Since and For

A common error is using since with a duration or for with a starting point.

Remember:

• since + starting point

• for + duration

For example:

• I have worked here since 2022.

• I have worked here for four years.

The first sentence identifies when the situation started, while the second describes its duration.

• Confusing By and Until

By and until are not interchangeable.

Use by when the sentence focuses on a deadline: Please send the email by Friday.

Use until when an action or situation continues up to a particular time: I will stay here until Friday.

A useful way to distinguish them is to ask whether the sentence is about completion before a deadline or continuation up to a time.

• Common Fixed Expressions

Some expressions are best learned as complete combinations because their prepositions do not always follow a simple rule.

Common examples include:

• at night

• at noon

• at midnight

• in the morning

• in the afternoon

• in the evening

There are also differences between general periods and specific occasions. For example, at Christmas refers to the holiday period, while on Christmas Day refers to a particular day.

Choosing the correct preposition is an important part of building grammatically accurate sentences. If you are also reviewing common structures used to express reasons, see our guide to Because and Because of for a detailed comparison and practice exercises. 

Preposition of Time Exercises

Practicing prepositions of time helps reinforce the difference between in, on, at, and other common expressions. The exercises below cover the main rules discussed in this article.

Exercise 1: Choose In, On, or At

Choose the correct preposition.

1. My birthday is ___ September.
2. We have a meeting ___ Monday.
3. The class starts ___ 9 a.m.
4. She usually studies ___ the evening.
5. They moved here ___ 2020.
6. We usually go on vacation ___ summer.
7. The train arrives ___ noon.
8. I have an appointment ___ Friday morning.

Exercise 2: Choose the Correct Preposition

Choose the most appropriate preposition.

1. I have lived here ___ 2021.
2. She has studied English ___ three years.
3. Please finish the report ___ Friday.
4. We stayed there ___ two weeks.
5. He fell asleep ___ the movie.
6. The office is open ___ 8 a.m. ___ 5 p.m.
7. I will wait here ___ 6 p.m.
8. The course begins ___ September.

Exercise 3: Correct the Mistakes

Each sentence contains a mistake involving a preposition of time. Rewrite it correctly.

1. I was born on 2002.
2. The class begins in 8 a.m.
3. She has worked here since five years.
4. Please finish the project until Friday.
5. I usually study in Monday morning.

Answers and Explanations

Exercise 1

1. in
2. on
3. at
4. in
5. in
6. in
7. at
8. on

Months, years, and seasons generally take in, days and specific dates take on, and specific times take at.

Exercise 2

1. since
2. for
3. by
4. for
5. during
6. from / to
7. until
8. in

The answers depend on the relationship between the action and the time expression. Since introduces a starting point, for a duration, by a deadline, during a period or event, and until a point up to which something continues.

Exercise 3

1. I was born in 2002.
2. The class begins at 8 a.m.
3. She has worked here for five years.
4. Please finish the project by Friday.
5. I usually study on Monday morning.

Preposition of Time Worksheet and Game

A preposition of time worksheet can help learners review the rules through activities such as choosing the correct preposition, completing sentences, matching time expressions, and correcting mistakes.

A simple preposition of time game can also make revision more interactive. For example, learners can be given a time expression such as “Monday”, “8 p.m.”, or “December” and choose on, at, or in as quickly as possible.

Learners can also combine time and place exercises to reinforce the different uses of in, on, and at. Comparing expressions such as in 2025 / in London, on Monday / on the table, and at 8 a.m. / at the station can help clarify how context affects the meaning of each preposition.

Conclusion

Understanding preposition of time becomes easier when you focus on the type of time expression that follows each preposition. The three most important forms are in, on, and at: in is commonly used with months, years, seasons, and longer periods; on with days and dates; and at with specific times and several fixed expressions.

You should also understand the differences between since and for, by and until, and during and for. Paying attention to expressions such as at night, in the morning, on Monday morning, at Christmas, and on Christmas Day can help you avoid common mistakes.

Regular practice with targeted exercises and worksheets will make these patterns easier to recognize and use naturally in both English writing and everyday communication.

FAQ About Preposition of Time

Can I use “on” with a month?

Normally, no. We use in with months, such as in September or in December. We use on when referring to a specific date, such as on September 15.

Should I say “in the morning” or “on the morning”?

Both are possible, but they are used differently. In the morning refers to the morning in general, while on the morning of… or on Monday morning refers to a particular morning.

Is it “at the weekend” or “on the weekend”?

Both forms are used. At the weekend is common in British English, while on the weekend and on weekends are common in American English.

Do I use a preposition before “next week” or “last year”?

Normally, no. We say next week, last year, this month, and every day without adding in, on, or at.

What is the difference between “by” and “until”?

By refers to a deadline, while until describes something that continues up to a particular time. For example, finishing it by Friday refers to a deadline, while stay here until Friday describes continuation.

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