Mastering English grammar requires understanding how time is expressed. We use at for a precise time, in for months and years, and on for days and dates correctly in sentences.
We use:
at for a PRECISE TIME
in for MONTHS, YEARS, CENTURIES and LONG PERIODS
on for DAYS and DATES
What is the Difference Between At, In, and On for Time?
| at PRECISE TIME |
in MONTHS, YEARS, CENTURIES and LONG PERIODS |
on DAYS and DATES |
|---|---|---|
| at 3 o'clock | in May | on Sunday |
| at 10.30am | in summer | on Tuesdays |
| at noon | in the summer | on 6 March |
| at dinnertime | in 1990 | on 25 Dec. 2010 |
| at bedtime | in the 1990s | on Christmas Day |
| at sunrise | in the next century | on Independence Day |
| at sunset | in the Ice Age | on my birthday |
| at the moment | in the past/future | on New Year's Eve |
How to Use Prepositions of Time in Sentences
Look at these examples:
I have a meeting at 9am.
The shop closes at midnight.
Jane went home at lunchtime.
In England, it often snows in December.
Do you think we will go to Jupiter in the future?
There should be a lot of progress in the next century.
Do you work on Mondays?
Her birthday is on 20 November.
Where will you be on New Year's Day?
What Are Standard Expressions Using At?
Notice the use of the preposition of time at in the following standard expressions:
| Expression | Example |
|---|---|
| at night | The stars shine at night. |
| at the weekend* | I don't usually work at the weekend. |
| at Christmas*/Easter | I stay with my family at Christmas. |
| at the same time | We finished the test at the same time. |
| at present | He's not home at present. Try later. |
*Note that in some varieties of English people say "on the weekend" and "on Christmas".
How to Use In and On in Common Expressions
Notice the use of the prepositions of time in and on in these common expressions:
| in | on |
|---|---|
| in the morning | on Tuesday morning |
| in the mornings | on Saturday mornings |
| in the afternoon(s) | on Sunday afternoon(s) |
| in the evening(s) | on Monday evening(s) |
What Are the Exceptions with Last, Next, Every, and This?
When we say last, next, every, this we do not also use at, in, on.
I went to London last June. (not in last June)
He's coming back next Tuesday. (not on next Tuesday)
I go home every Easter. (not at every Easter)
We'll call you this evening. (not in this evening)
Mini Quiz
Test your understanding with this quick quiz.
1. Choose the correct prepositions: "Let's meet _______ midday _______ Saturday."
at, at
in, on
at, on
2. Choose the correct prepositions: "The manager isn't here _______ present, but she'll be back _______ half an hour."
at, in
at, at
in, in
3. Which are correct? "You won't be working _______ Saturday nights _______ the future, will you?"
at, in
on, in
on, at
4. Which are correct? "I'm busy _______ moment, but I'll be free ______ evening."
at the, in this
in the, at this
at the, this
Key Takeaways
- Use at for precise times like clock times, noon, and specific holiday periods (at night, at Christmas).
- Use in for longer durations such as months, years, centuries, and parts of the day (in May, in 1990, in the morning).
- Use on for specific days and dates (on Sunday, on 6 March, on New Year's Day).
- Avoid using prepositions like at, in, or on before words like last, next, every, and this.
Quick Practice
Test your skills! Write your answers in the comments below:
- What preposition of time fits best in this sentence: "My graduation ceremony is _______ Friday"?
- Can you complete this phrase using the correct rule: "We usually eat dinner _______ night"?
FAQ
When should I use "at" instead of "in" or "on"?
We use at specifically for precise times, such as clock times (at 3 o'clock), specific points during the day (at noon, at sunrise), and standard expressions like at night or at the weekend.
How do I know whether to use "in" or "on" for days and months?
We use in for months, years, centuries, and long periods (in May, in 1990), whereas we use on for specific days and dates (on Sunday, on 6 March).
Can I use prepositions with words like "next" or "last"?
No. When we use words like last, next, every, this, we do not use prepositions like at, in, or on right before them (e.g., we say "last June", not "in last June").