Prepositions of time: in, on and at
Learn when to use in, on and at with times, days, dates, months and years, when to use no preposition, and how for, since, by and until work.
In this lesson
We use the prepositions in, on and at to say when something happens. Use at for exact times (at 7 o’clock), on for days and dates (on Monday, on 4 February) and in for longer periods such as months, years and seasons (in May, in 2025). Some time words take no preposition.
Key point
Go from small to big: at for a point in time, on for a day or date, and in for a longer period. Do not use in, on or at before next, last, this, every, today, tomorrow or yesterday.
How do you choose in, on or at?
Think about the size of the time. A clock time is very small, so it takes at. A day is bigger, so it takes on. Months, years and seasons are bigger still, so they take in.
| Preposition | Use it for | Examples |
|---|---|---|
| at | clock times, night, meal times, holiday periods and fixed phrases | at 6 o’clock, at half past nine, at night, at lunchtime, at Christmas, at the moment |
| on | days, dates and special days | on Monday, on 4 February, on my birthday, on Independence Day |
| in | months, years, seasons, decades, centuries and parts of the day | in May, in 2025, in the rainy season, in the 1990s, in the 21st century, in the morning |
When do you use at?
Use at with exact times and with short points in the day. We also use it in some fixed phrases, such as at the moment, at the same time and at the end of the month.
Examples
- The train to Kandy leaves at 7.15.
- Nimal usually goes to bed at 10 o’clock.
- We have a short break at lunchtime.
- I’m sorry, I’m busy at the moment.
When do you use on?
Use on with days of the week, dates and special days. Add an -s to the day to talk about a habit: on Mondays means every Monday.
Examples
- Sri Lanka celebrates Independence Day on 4 February.
- Many offices in Sri Lanka are closed on Poya days.
- What are you doing on Saturday?
- Sanduni plays badminton on Wednesdays.
When do you use in?
Use in with longer periods of time: months, years, seasons, decades and centuries. We also use it with the parts of the day, and to say how soon something will happen.
Examples
- Sanduni was born in 2001.
- It often rains in Colombo in May.
- I drink a cup of tea in the morning.
- Hurry up! The bus leaves in ten minutes.
Tip
We say in the morning, in the afternoon and in the evening, but at night. When you name a day, use on: on Monday morning, on Friday night.
Note
British English says at the weekend, and American English says on the weekend. Both are correct, but never say in the weekend.
When do you use no preposition?
Do not use in, on or at before next, last, this and every, or before today, tonight, tomorrow and yesterday. To talk about plans, see our lesson on the simple future tense.
Examples
- I’ll see you next Friday.
- We moved to Galle last year.
- She goes to the gym every morning.
- Are you free tonight?
Common mistake
I’ll see you on next Monday. → I’ll see you next Monday. Next already tells us the time, so we do not need a preposition.
How do you use for, since, during, by and until?
These prepositions also talk about time. Learn them as a group, because learners often mix them up.
| Word | Meaning | Example |
|---|---|---|
| for | a length of time | I have lived in Kandy for five years. |
| since | from a point in the past until now | I have lived in Kandy since 2020. |
| during | at some time in, or all through, a period | Nimal fell asleep during the film. |
| by | not later than | Please send me the report by Friday. |
| until | up to a time, and then it stops | The shop is open until nine o’clock. |
Note
Use for and since mostly with the present perfect tense. For gives a length of time (for two hours) and since gives the starting point (since Monday), so never say since two hours. By means “at or before”, and until means “all the time up to”: Finish your homework by six. You can play until six.
Practise prepositions of time
Choose in, on, at or no preposition, then try for, since, during, by and until. You will see the answer after each question.
Time expressions like on Mondays and every morning often go with habits, so they appear a lot in the simple present tense. The same three words also tell us where things are, which you can learn in our lesson on prepositions of place. To learn the names of days and months, see days, months and seasons. For more practice, read the Cambridge Dictionary guide to at, on and in for time or try the British Council exercises on prepositions of time.
Summary
- Use at for clock times, at night and fixed phrases: at 7.15, at the moment.
- Use on for days, dates and special days: on Monday, on 4 February.
- Use in for months, years, seasons and parts of the day: in May, in the morning.
- Use no preposition before next, last, this, every, today, tomorrow and yesterday.
- For is a length of time, since is a starting point, and by is a deadline.
Frequently asked questions
Is it “at the weekend” or “on the weekend”?
Both are correct. British English uses at the weekend and American English uses on the weekend. Do not say in the weekend.
Why do we say “in the morning” but “at night”?
There is no simple rule, so learn them as fixed phrases. Remember that a named day changes the preposition to on: on Monday morning, on Saturday night.
Do I need a preposition before “next week”?
No. Do not use in, on or at before next, last, this or every. Say I’ll call you next week, not on next week.
What is the difference between for and since?
For tells us how long something lasts: for three years. Since tells us when it started: since 2022. Both often go with the present perfect.
Practise this lesson
12 questions
