Prepositions of Time: In, On and At with Exercises

Learn when to use in, on and at for time with clear rules, common expressions, learner mistakes and practice exercises with answers.

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Introduction to Prepositions of Time: In, On and At

The prepositions in, on and at are commonly used to talk about time in English, but learners often confuse them.

Compare:

in the morning
on Monday
at 7 o’clock

A useful general rule is:

  • in for longer periods of time
  • on for days and dates
  • at for specific times and certain fixed expressions

However, there are several important exceptions, so it is better to learn the main patterns and common expressions rather than rely on one rule alone.

In, on and at: quick comparison

Here is the basic difference:

Quick comparison of in, on and at for time
Preposition Main use Examples
in months, years, seasons, longer periods and parts of the day in July, in 2026, in winter, in the morning
on days and dates on Monday, on 15 May, on my birthday
at clock times and specific points in time at 7:30, at noon, at midnight, at night

Think about the difference like this:

in = a larger period

on = a particular day

at = a precise point

For example:

I was born in 1995.
The meeting is on Tuesday.
The meeting starts at 10:00.

When to use in

Use in with longer periods of time.

Months

in January
in August
in December

Example:

We’re travelling to Europe in September.

Years

in 2005
in 1990
in 2026

Example:

She started university in 2022.

Decades and centuries

in the 1990s
in the 21st century
in the 1800s

Example:

The building was constructed in the 19th century.

Seasons

in spring
in summer
in autumn
in winter

Example:

It gets very cold here in winter.

Parts of the day

Use in with:

in the morning
in the afternoon
in the evening

Examples:

I usually exercise in the morning.
We normally eat dinner in the evening.

The main exception is:

at night

not:

in the night

We use in the night only in more specific situations, often when something happens during the night:

I woke up several times in the night.

But for a general time expression:

I usually read at night.

Longer periods

We also use in with expressions such as:

in the past
in the future
in the holidays
in my childhood
in the early 2000s

Example:

People may work fewer hours in the future.

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When to use on

Use on with days and dates.

Days of the week

on Monday
on Friday
on Sunday

Example:

I have an appointment on Thursday.

Dates

on 12 June
on 25 December
on 1 January

Example:

The course starts on 3 September.

Specific days

Use on when the expression refers to a particular day:

on my birthday
on New Year’s Day
on Christmas Day
on the first day of school

Example:

We usually go out for dinner on my birthday.

Day + part of the day

If a part of the day is connected to a specific day, use on:

on Monday morning
on Friday evening
on Sunday afternoon

Compare:

I usually work in the morning.
I have a meeting on Monday morning.

The specific day changes the preposition from in to on.

When to use at

Use at for specific points in time.

Clock times

at 6:00
at 8:30
at 11 o’clock

Example:

The lesson starts at 7:00.

Noon and midnight

at noon
at midnight

Example:

The train arrives at midnight.

Night

Use:

at night

Example:

I don’t usually drink coffee at night.

This is a common exception because we say:

in the morning
in the afternoon
in the evening

but:

at night

Other fixed expressions with at

Common examples include:

at the weekend
at lunchtime
at breakfast
at sunset
at sunrise
at the moment

Example:

I’m quite busy at the moment.

In British English, at the weekend is very common.

You will also hear on the weekend in American English.

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No preposition with next, last, this and every

Do not use in, on or at before many time expressions containing:

  • next
  • last
  • this
  • every

Correct:

I’ll see you next Monday.
We travelled to Spain last summer.
I’m very busy this week.
I exercise every morning.

Incorrect:

on next Monday
in last summer
in this week
in every morning

The same rule applies to expressions such as:

yesterday
today
tomorrow

For example:

I saw him yesterday.

Not:

on yesterday
I’ll call you tomorrow morning.

Not:

on tomorrow morning

Common time expressions

Here are some useful expressions to learn as complete phrases.

With in

  • in the morning
  • in the afternoon
  • in the evening
  • in January
  • in summer
  • in 2026
  • in the future
  • in the past
  • in a few minutes
  • in two weeks

With on

  • on Monday
  • on Friday morning
  • on 10 May
  • on my birthday
  • on Christmas Day
  • on the weekend — mainly American English

With at

  • at 8:00
  • at night
  • at noon
  • at midnight
  • at lunchtime
  • at the weekend — common British English
  • at the moment
  • at sunrise

Also notice:

in two hours

means two hours from now.

For example:

I’ll call you in two hours.

This does not mean during a two-hour period.

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Common mistakes

Saying at Monday

Incorrect:

I’ll see you at Monday.

Correct:

I’ll see you on Monday.

Use on for days.

Saying in 7 o’clock

Incorrect:

The meeting starts in 7 o’clock.

Correct:

The meeting starts at 7 o’clock.

Use at for exact clock times.

Saying on July

Incorrect:

We’re going away on July.

Correct:

We’re going away in July.

Use in for months.

Saying in night

Incorrect:

I study in night.

Correct:

I study at night.

Saying in Monday morning

Incorrect:

I’ll call you in Monday morning.

Correct:

I’ll call you on Monday morning.

When a specific day is included, use on.

Adding a preposition before next

Incorrect:

I’m going there on next Friday.

Correct:

I’m going there next Friday.

Confusing at the weekend and on the weekend

Both exist, but there is a regional difference.

British English commonly uses:

at the weekend

American English commonly uses:

on the weekend

If you are learning British English, at the weekend is the safer default.

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Exercises and answers

Exercise 1: Choose in, on or at

  1. The lesson starts ___ 9:30.
  2. I was born ___ 1998.
  3. We usually visit my parents ___ Sunday.
  4. She studies ___ the evening.
  5. I don’t like driving ___ night.
  6. The meeting is ___ Monday morning.
  7. We’re going away ___ August.
  8. The shop closes ___ midnight.
  9. He started his new job ___ 15 March.
  10. It gets very hot here ___ summer.

Exercise 2: Add a preposition if necessary

Write in, on, at or — if no preposition is needed.

  1. I’ll see you ___ next week.
  2. We went there ___ last Friday.
  3. I normally exercise ___ the morning.
  4. She has a class ___ every Tuesday.
  5. They arrived ___ midnight.
  6. I’m working from home ___ this afternoon.
  7. We’ll meet ___ Friday evening.
  8. I called him ___ yesterday.
  9. The course begins ___ September.
  10. I’ll finish the work ___ tomorrow morning.

Exercise 3: Correct the mistakes

  1. I was born on 2001.
  2. We usually eat dinner at the evening.
  3. I’ll see you at Monday.
  4. She works in night.
  5. The meeting is in 10 o’clock.
  6. I’m going there on next Saturday.
  7. We met in Friday afternoon.
  8. He usually goes running in the weekend.

Answers and explanations

Exercise 1

  1. at 9:30 — exact time
  2. in 1998 — year
  3. on Sunday — day
  4. in the evening — part of the day
  5. at night — fixed expression
  6. on Monday morning — specific day
  7. in August — month
  8. at midnight — specific point in time
  9. on 15 March — date
  10. in summer — season

Exercise 2

  1. — next week
  2. — last Friday
  3. in the morning
  4. — every Tuesday
  5. at midnight
  6. — this afternoon
  7. on Friday evening
  8. — yesterday
  9. in September
  10. — tomorrow morning

Remember: expressions with next, last, this, every, yesterday, today and tomorrow normally do not need a time preposition.

Exercise 3

  1. I was born in 2001.
  2. We usually eat dinner in the evening.
  3. I’ll see you on Monday.
  4. She works at night.
  5. The meeting is at 10 o’clock.
  6. I’m going there next Saturday.
  7. We met on Friday afternoon.
  8. He usually goes running at the weekend.

The simplest way to remember prepositions of time in, on and at is to start with the main pattern: use in for longer periods, on for days and dates, and at for exact times. Then learn important expressions such as in the morning, on Monday morning and at night as complete phrases.

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