In or At or On with Date and Time? (Full Explanation)

Using prepositions can get complicated, sometimes. This is especially true when you’re trying to figure out which preposition to use with a date or time. Here, we’ll be discussing when to use the prepositions “in”, “at”, and “on” with date or time.

In or At or On with Date and Time?

“In” is used when it’s followed by a month, year, season, or certain parts of the day (i.e., morning, afternoon, evening). “At” is used when there’s a specific time and at certain parts of the day (i.e., noon, night, midnight). “On” is used for dates and days of the week.

in at on date time

All three prepositions are used for different purposes when used with dates and times. These are not interchangeable with one another.

“In” is the preposition to use when the word that follows is any of the following: a month, a year, a season, a part of the day (i.e., morning, afternoon, evening).

On the other hand, the preposition “at” is used when it is followed by a specific time (e.g., 12:45), and on certain parts of the day (i.e., noon, night, midnight).

Finally, “On” is the preposition used for dates (e.g. June 5) and days of the week.

These prepositions can be used in the same sentence, as seen below:

  • In November, maybe on a Saturday, we should meet up at midnight to hook up.

When to Use “In”

When referring to a month, year, season, or certain parts of the day (i.e., morning, afternoon, evening), the preposition “in” should be used.

“In” is what you should use when you are referring to a month, whether at the start of the sentence or the end. Take a look at the sentences below:

  • Vincent will be turning ten in March.
  • In April, Cassidy will be moving to Australia.

You also use “in” when referring to seasons, as seen in the following sentences:

  • In the summer, we go visit our grandparents.
  • Her sister Beth passed away in the winter.
  • Tam last saw her in Autumn, when she left for the city.

The same is true when the season ends with “-time”:

  • Elise fell in love with Jonathan in the summertime.

Certain parts of the day can only be described using the preposition “in”: morning, afternoon, and evening. Examples can be found below:

  • My sister shouldn’t go out drinking tonight, she has a class in the morning.
  • Let’s meet up with Hannah in the afternoon.

The rule remains the same even if the words “morning”, “afternoon”, and “evening” are modified by an adjective:

  • He did not expect to be coming home in the early morning.

This also works for phrases such as “the middle of the day”:

  • Peter should not be drunk in the middle of the day.
  • What are you doing calling my husband in the middle of the night?

When to Use “At”

When referring to a specific time or certain parts of the day not described by “in” (i.e., noon, night, midnight), the preposition “at” should be used.

The preposition “at” should be used when referring to a specific time. This applies when the time is in number form, as seen below:

  • I woke up at 8:33 am this morning, so I was late for school.
  • At 12:45 pm, my boss called to find out where I was.

The same rule applies when the time is spelled out using words:

  • At seven in the morning, I woke up to my sister blasting her music at full volume.
  • I’ll be off work by five, so are you okay to meet up at eight-thirty?
  • My ex-girlfriend and I had dinner together at six o’clock last night.
  • Sarah left the apartment at half-past eight this morning, but she still hasn’t shown up to work.

When the time is modified by an adjective like “around”, “at” is still the preposition to use:

  • Mike and I will be there at around seven.

This also works if the time is in both numerical form and spelled out at the same time:

  • Don’t forget, Danielle has her ballet recital at 8 o’clock tomorrow.

Finally, the preposition “at” is also used when referring to certain parts of the day not already described by the preposition “in” (i.e., noon, night, midnight), Take a look at the examples below:

  • I wear this particular eyeshadow only at night because it’s too dark for the daytime.
  • At midnight, Mary left the party, which is why they’re calling her “Cinderella”.
  • If you eat your pizza now, you’ll have nothing to eat at noon.

When to Use “On”

When referring to dates and days of the week, the preposition to use is “on”.

You use the preposition “on” when you have a specific date to describe. The date should contain at least a month and a day. Take a look at the following examples:

  • On March 5, I took my driver’s test and finally got my license.
  • Kim had a date with Ray on April 11 and another one with his brother Troy a week later.
  • Tracy and Carl married on October 3.

The same rule applies when the date is written before the month, as in the sentence below:

  • On the 5th of March, I passed the medical boards.

When a date contains a month, a day, and a year, “on” is still the preposition to use:

  • I last saw my best friend on June 14, 2012.
  • On September 6, 2020, we passed our proposal for our dissertation.

This also works if you are describing a specific date with words, such as in the following sentences:

  • My family will be together on Christmas Eve, I just know it.
  • On her birthday, Lyra was given a puppy.
  • They always meet on the first Sunday of the month.

Last but not least, the preposition “on” is used when referring to days of the week:

  • On Wednesday, I had a cheeseburger.
  • She’ll be meeting with me on Friday.

Final Thoughts

When describing a month, year, season, or certain parts of the day (i.e., morning, afternoon, evening), “in” is used. “At” is used for specific times and certain parts of the day (i.e., noon, night, midnight). Finally, “on” is used for days of the week and specific dates.