Prepositions of Time

The complete guide to expressing when actions occur in English

A preposition of time indicates temporal relationships, showing when something happens in relation to another point in time. These prepositions answer questions like "When?", "How long?", and "How often?"

Why Prepositions of Time Matter

Proper use of time prepositions is essential for clear communication in academic writing, professional correspondence, and standardized tests. Misusing these small words can completely change the meaning of temporal references.

Quick Examples:
  • We'll meet at 3:00 PM.
  • The conference is on Monday.
  • She graduated in 2020.
  • I've been working since morning.
  • We waited for two hours.
Key Characteristics:
  • Establish temporal relationships between events
  • Often paired with specific time expressions
  • Can change meaning based on context
  • Essential for scheduling and historical references
  • Frequently tested in standardized exams

Core Prepositions of Time

1. AT

Used for precise clock times and specific points in time:

Examples:
  • at 9:30 AM/PM
  • at noon/midnight
  • at night (exception to clock time rule)
  • at the moment
  • at sunrise/sunset
  • at the same time
  • at the weekend (British English)
  • at Christmas/Easter (refers to the period)

2. ON

Used for days and dates:

Examples:
  • on Monday/Tuesday/etc.
  • on January 15th
  • on Christmas Day (specific day)
  • on my birthday
  • on the weekend (American English)
  • on time (punctual, compare with "in time")
  • on the morning/afternoon/evening of May 5th

3. IN

Used for longer periods (months, years, seasons, centuries):

Examples:
  • in January/February/etc.
  • in 2023
  • in the 21st century
  • in summer/winter/etc.
  • in the morning/afternoon/evening
  • in time (early enough, compare with "on time")
  • in the past/future
  • in six months (future reference)

4. SINCE

Indicates the starting point of an ongoing action:

Examples:
  • I've lived here since 2015.
  • She's been working since morning.
  • We haven't met since last Christmas.
  • They've been married since June.

5. FOR

Indicates duration or how long something lasts:

Examples:
  • We waited for three hours.
  • He's been absent for a week.
  • I studied French for five years.
  • The project lasted for months.

6. FROM...TO/UNTIL

Indicates a time range:

Examples:
  • The store is open from 9 AM to 5 PM.
  • I worked from Monday until Friday.
  • She lived in Paris from 2010 to 2015.

7. DURING

Indicates when something happens within a period:

Examples:
  • She fell asleep during the movie.
  • Many changes occurred during the war.
  • We met several times during the conference.

8. BY

Indicates a deadline or latest possible time:

Examples:
  • Please submit your report by Friday.
  • I'll be finished by 5 o'clock.
  • She had completed the project by the end of May.

9. BEFORE/AFTER

Indicate sequence in time:

Examples:
  • Please arrive before 8:00 AM.
  • We'll discuss this after lunch.
  • She left before sunrise.
  • The results came after three days.

10. UNTIL/TILL

Indicate the end point of a period:

Examples:
  • I'll wait until you're ready.
  • The museum is open till 7 PM.
  • He worked until midnight.

11. WITHIN

Indicates something happening inside a time boundary:

Examples:
  • We'll respond within 24 hours.
  • The package should arrive within a week.
  • She completed the task within the deadline.

Detailed Usage Rules

1. AT vs. ON vs. IN

The three most common prepositions follow this hierarchy:

Clock Time → AT:

at 3:00 PM, at midnight

Days/Dates → ON:

on Monday, on July 4th

Longer Periods → IN:

in October, in 2025, in winter

2. Special Cases and Exceptions

Parts of the Day

  • in the morning/afternoon/evening
  • at night
  • on Tuesday morning (with specific day)

Holidays

  • at Christmas (the holiday period)
  • on Christmas Day (December 25th specifically)
  • on New Year's Eve/Day

Expressions Without Prepositions

Some time expressions don't require prepositions:

  • I'll see you next week.
  • We met last summer.
  • She's arriving this afternoon.
  • They left every day at noon.

3. FOR vs. SINCE

"For" indicates duration, "since" indicates starting point:

Examples:
  • I've lived here for five years. (duration)
  • I've lived here since 2018. (starting point)
  • We've been waiting for hours.
  • We've been waiting since 9 AM.

4. DURING vs. WHILE

"During" is followed by a noun, "while" by a clause:

Correct:
  • She fell asleep during the lecture. (noun)
  • She fell asleep while the professor was speaking. (clause)
Incorrect:
  • ✖ She fell asleep during the professor was speaking.
  • ✖ She fell asleep while the lecture.

5. BY vs. UNTIL

"By" means no later than, "until" means continuing up to:

  • Finish the report by Friday. (deadline)
  • I'll be working until Friday. (continuous action)

6. IN vs. WITHIN

"In" often refers to future time, "within" to boundaries:

  • I'll be ready in 10 minutes. (after 10 minutes)
  • I'll respond within 10 minutes. (before 10 minutes pass)

Advanced Usage: Nuances and Subtleties

1. "On time" vs. "In time"

  • The train arrived on time. (as scheduled)
  • We arrived in time for the opening remarks. (early enough)

2. "At the weekend" (UK) vs. "On the weekend" (US)

  • British: What did you do at the weekend?
  • American: What did you do on the weekend?

3. "In the beginning" vs. "At the beginning"

  • In the beginning, we struggled with the software. (general early period)
  • At the beginning of the meeting, we introduced ourselves. (specific starting point)

4. "By day" vs. "By night"

  • He's a lawyer by day and a musician by night.

5. "In" for Future Time

  • The project will be completed in six months. (six months from now)

6. Omission in Newspaper Headlines

  • Standard: The president resigned on Monday.
  • Headline: President resigns Monday.

Prepositions of Time in Academic Writing

1. Historical References

  • The treaty was signed on June 28, 1919.
  • In the 19th century, industrialization accelerated.

2. Research Timelines

  • Data was collected from January to March 2023.
  • Participants were observed during the testing period.

3. Citations and References

  • As Smith (2019) noted, the theory was developed in the early 2000s.

4. Common Academic Collocations

  • At present, the evidence suggests...
  • In recent years, scholars have...
  • During the course of the experiment...
  • By the end of the century...

Common Errors and How to Avoid Them

1. Incorrect: "In Monday"

Correct:

On Monday

2. Incorrect: "At January"

Correct:

In January

3. Incorrect: "Since two hours"

Correct:

For two hours

4. Incorrect: "During she was speaking"

Correct:

While she was speaking

5. Incorrect: "I'll call you within five minutes" (when meaning future time)

Correct:

I'll call you in five minutes.

Standardized Test Focus (IELTS, SAT, GRE, GMAT, etc.)

1. Error Identification Questions

Identify the error:

"The conference will take place (A) in (B) Friday (C) at the convention center (D)."

Answer: (B) - should be "on Friday"

2. Sentence Completion Questions

Choose the correct preposition:

"The results will be announced _____ June 15th."

  • A) at
  • B) on
  • C) in
  • D) by

Answer: B) "on" (for specific dates)

3. Writing Section Tips

  • Use precise time prepositions in task 1 (graphs/charts with timelines)
  • Maintain consistency in essay timelines (past vs. present perfect with "since/for")
  • Vary time expressions for higher scores

4. Speaking Test Tips

  • Use natural time expressions in Part 1 (personal experiences)
  • Demonstrate range in Part 3 (abstract discussions of past/future)
  • Practice common collocations ("in recent years," "at the moment")

Practice Activities

1. Fill-in-the-Blank

Complete with correct prepositions:

  1. We have a meeting _____ 9:00 AM _____ Monday.
  2. She lived in Paris _____ 2018 _____ 2022.
  3. I'll be on vacation _____ July.
Answers:
  1. at, on
  2. from, to/until
  3. in

2. Error Correction

Correct these sentences:

  1. The project is due in Friday.
  2. We've been waiting since two hours.
  3. During I was cooking, the phone rang.
Answers:
  1. The project is due on Friday.
  2. We've been waiting for two hours.
  3. While I was cooking, the phone rang.

3. Academic Writing Practice

Rewrite this paragraph with appropriate time prepositions:

"The study began (at/in) March 2022. Data was collected (during/while) six months. (At/On) the beginning, participants were interviewed. (In/By) the end of September, all results were analyzed."

Answer:

"The study began in March 2022. Data was collected for six months. At the beginning, participants were interviewed. By the end of September, all results were analyzed."

Comprehensive Reference Table

Preposition Usage Example Common Mistakes
at Clock times, specific points at 3:00 PM, at noon ✖ at Monday
on Days, dates on Tuesday, on July 4th ✖ on 2025
in Months, years, seasons in August, in 2024 ✖ in Monday
since Starting point since 2010, since noon ✖ since two hours
for Duration for three days ✖ for 2015
during Within a period during the meeting ✖ during he spoke
by Deadline by Friday ✖ by the morning
until Continuing up to until 5 PM ✖ until two hours

Final Checklist for Mastery

  • ✓ Mastered AT/ON/IN distinctions
  • ✓ Understand FOR/SINCE usage
  • ✓ Know DURING/WHILE difference
  • ✓ Can use BY/UNTIL correctly
  • ✓ Recognize common errors
  • ✓ Apply knowledge to test questions
  • ✓ Use appropriately in writing/speaking
Pro Tip:

When unsure, visualize time expressions on a timeline - "at" for points, "on" for specific days, "in" for containing periods.