At, on or in? Prepositions of time
Short answer: Use at for a clock time (at seven o’clock), on for a day or date (on Monday, on May 5th), and in for a month, a year, a season or a part of the day (in May, in 2026, in winter, in the morning). The exception is night: we say at night.
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At a glance
| Word | Used with | Examples |
|---|---|---|
| at | clock times, meal times, night | at 7 o’clock, at lunchtime, at night |
| on | days and dates | on Monday, on May 5th, on my birthday |
| in | months, years, seasons, parts of a day | in May, in 2026, in winter, in the evening |
In short
- at + a clock time: at 7 o'clock.
- on + a day: on Monday.
- in + a month or part of the day: in May, in the morning. But: at night.
What is the rule for “at 7, on Monday, in May: time words”?
The rule
at goes with a clock time, on with a day and in with a month or a part of the day.
How it looks
at 7 o'clock · on Monday · in May · in the morning
What it means
at, on and in tell when something happens.
When to use it
Use them to say when.
How it works
- Is it a point on the clock? Use at.
- Is it one day or one date? Use on.
- Is it a longer period such as a month, a season or a year? Use in.
- Remember the special cases: at night, at the weekend (British English), but on the weekend (American English).
Examples of “at 7, on Monday, in May: time words”
- We have lunch at twelve o'clock.
at + a clock time. - I swim on Saturday.
on + a day. - It is hot in May.
in + a month. - I read in the evening.
in + a part of the day. - The class starts at nine.
at + a clock time. - My birthday is on June 3rd.
on + a date. - It snows in winter.
in + a season. - We eat dinner in the evening.
in + a part of the day.
Common mistakes with “at 7, on Monday, in May: time words”
in Monday→ on Monday
Use on with a day.on May→ in May
Use in with a month.in night→ at night
We say at night.I get up on 6 o’clock.→ I get up at 6 o’clock.
Use at with a clock time.I was born on 2020.→ I was born in 2020.
Use in with a year.
Exceptions: watch out
- at night
night is different: we say at night, not in the night.
At, on, in for time and for place
The same three words are used for place. The idea is similar: at is a point, on is a surface or day, in is a space or period.
| Word | Time | Place |
|---|---|---|
| at | at 7 o’clock | at the door |
| on | on Monday | on the table |
| in | in May | in the room |
See also: Where is it? Prepositions of place
Check yourself
- Fill the gap: “We have lunch ___ noon.”
Show the answer
at noon is a point in time.
- Fill the gap: “I swim ___ Saturday.”
Show the answer
on Saturday is a day.
- Fill the gap: “It is hot ___ July.”
Show the answer
in July is a month.
How to practice “at 7, on Monday, in May: time words”
The interactive version adds step-by-step help, spoken instructions and a quick check. One rule card, one sound lesson and the first lesson of every stone are free to try; the rest is part of Full Access. See Full Access.
- Practice lesson: at 7, on Monday, in May: time words
Questions
Why “at night” but “in the morning”?
It is just a fixed pattern in English. Learn at night as one phrase.
What do I say for “weekend”?
In British English: at the weekend. In American English: on the weekend.
Do I use a preposition before “tomorrow” or “yesterday”?
No. Say I will call tomorrow, not on tomorrow.
More Sentence Building rules
- Subject + Verb: A sentence needs someone or something (the subject) and a verb: Birds fly.
- Verbs can have an object: Some verbs can have an object: the person or thing that gets the action.
- Present simple: I, you, we, they: For things we do again and again, and for likes, use the plain action word with I, you, we and they.
- Present simple: he, she, it + -s: With he, she, it or one name, the action word usually adds -s.
- Negatives: not with be and can: To say no with am, is, are or can, add not: I am not, she isn't, they aren't, it can't.
- Negatives: don't and doesn't: To say no with an action word, use don't or doesn't and then the plain action word.
Used in these writing topics
Part of the 📘 Grammar tool. Level G2: Sentence Building. Đọc bằng tiếng Việt.
Written for English learners by the English for Fun team. How we write our lessons · Last updated 2026-11-05.
Reviewed by Chinh Q. Hoang, PhD, founder, English for Fun · 2026-10-30
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