Practice
On Monday or at Monday: which is correct?
Your manager says, The meeting is on Monday at 9:00. Monday is the day, so it takes on. Nine o'clock is the time, so it takes at. The two prepositions can appear in the same sentence, but they do different jobs.
Use on Monday for a particular Monday or on Mondays for a regular habit, and use at only with a time or an event that needs it.
Read and practice
Read the examples and try the written questions in this guide. Listening recordings are not available for this lesson yet.
Try the written questions
on Monday at nine /ɑn ˈmʌndeɪ æt naɪn/
The short answer
Say on Monday when you mean the day. Say at 8:30 when you mean the time. For a regular plan, use on Mondays. Do not use at Monday simply because the activity happens during that day.
The class starts on Monday at 8:30.
Why it works: On introduces the day, and at introduces the clock time.
5 more examples
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I will send the contract on Monday.
Monday is the day when the action will happen, so on is the normal preposition.
Not this:I will send the contract
at 10:00on Monday. What changes: At introduces the exact time, while on Monday still introduces the day. -
The library is closed on Mondays.
The plural form shows a regular weekly pattern rather than one specific day.
Not this:The library closes
at 6:00on Monday. What changes: At gives the clock time for one Monday. -
We moved the interview to Monday afternoon.
The phrase names a part of Monday. In ordinary conversation, to Monday afternoon is also natural after moved.
Not this:The interview is
on Monday afternoon. What changes: On is used when the sentence states when the interview will take place. -
She spoke at the Monday meeting.
At introduces the event, and Monday describes which meeting it was.
Not this:She spoke
on Monday. What changes: Here Monday is the day itself, so the sentence uses on. -
Please arrive on Monday by 9:00.
On names the day of arrival. By 9:00 gives a deadline, not the time when the person must arrive exactly.
Not this:Please arrive
at 9:00on Monday. What changes: At is right when the instruction gives an exact arrival time.
Read the full guide
Look first at the word after the preposition. A named day normally needs on. A clock time normally needs at. When Monday is part of a longer noun phrase, the preposition may belong to that whole phrase instead: at the Monday meeting means at a meeting, not at a day.
Name a day with on
Use on before the name of a day. This is the usual pattern for appointments, plans, and past events. The day answers the question When?
Our new course begins on Monday.
Monday is the day when the course begins, so on is the correct choice.
Complete the plan: The office will reopen ___ Monday.
Use on: The office will reopen on Monday.
Use at for a clock time
Use at when the sentence gives a precise time. A day and a time can appear together. Keep the two choices separate: on for the day and at for the time.
The train leaves at 7:15 on Monday.
At 7:15 tells us the exact time. On Monday tells us the day.
Choose the preposition for a time: The video call starts ___ noon.
Use at: The video call starts at noon.
Use plural Mondays for a habit
Use on Mondays when something happens every Monday or on many Mondays. The plural word shows a routine. A singular Monday usually refers to one particular day that the listener can identify from the context.
I work from home on Mondays.
The plural Mondays shows that working from home is part of a weekly routine.
Choose the form for a regular class that meets every week.
Write on Mondays: The class meets on Mondays.
Read the whole phrase after at
At can appear before a noun phrase that contains Monday. In at the Monday meeting, at introduces the meeting as an event. Monday only describes which meeting. This pattern does not support at Monday when you mean the day alone.
We decided the budget at the Monday meeting.
The decision happened at a meeting. The word Monday identifies that meeting.
Choose the phrase for something said during a meeting held on Monday.
Use at the Monday meeting. Do not write at Monday when the day is the only idea.
Do not confuse on with by
On Monday says that an action happens during Monday. By Monday says that Monday is the latest possible time for an action. The difference matters when you make a deadline or an appointment.
Please send the form by Monday.
The form can arrive before Monday, but it must arrive no later than Monday.
Choose the phrase for a meeting that will happen during Monday, not before it.
Use on Monday: We will meet on Monday.
Before you go
Remember this
Use on Monday for a day and on Mondays for a repeated Monday schedule. Use at for a clock time, such as at 9:00. You may hear at the Monday meeting because at belongs to meeting. For the day by itself, choose on Monday.
Practice with the written examples
You can practice with the written questions in the Learn tab. Each answer includes an explanation.
Try the written questionsListening test not available yet
This lesson does not have the recordings needed for a listening test. Use the written questions in the guide to check your understanding.
Try the written questionsQuestions about "On Monday or at Monday: which is correct?"
Is at Monday correct?
Not when Monday is the day by itself. Use on Monday for a particular day. At is used for a clock time, such as at 8:00, or as part of a longer phrase such as at the Monday meeting, where at introduces the meeting.
I will send the contract on Monday.
Should I say on Monday or on Mondays?
Use on Monday for one particular Monday. Use on Mondays for a regular pattern. For example, a clinic may be open on Monday next week but closed on Mondays as a usual rule.
I will send the contract at 10:00 on Monday.
Can I say I will see you Monday?
Yes. In informal English, speakers often omit on before a day name. On Monday is the full, neutral form and is useful when you want to make the time relationship explicit.
The library is closed on Mondays.
Why can I say at the Monday meeting?
At introduces the event, meeting. Monday acts as an adjective that identifies which meeting you mean. The phrase does not use at directly before the day name.
The library closes at 6:00 on Monday.
What is the difference between on Monday and by Monday?
On Monday means the action happens during Monday. By Monday means Monday is the latest deadline, so the action can happen earlier. Use on for a scheduled day and by for a deadline.
We moved the interview to Monday afternoon.