Prepositions of time tell us when something happens. Like their counterparts for place, in, on and at are the three core prepositions here, but the rules that govern them are entirely different, based on the size and type of the time period, not physical space.
atPrecise clock times and specific points: at 6pm, at night, at Christmas
onDays and dates: on Monday, on 5 May, on my birthday
inLonger periods: in July, in 2027, in the morning
Example"The meeting is at 10am on Tuesday in March."
Common Mistake"I was born in Monday" instead of "on Monday"
3. in / on / at — The Core Three
Preposition
Use
Examples
at
Precise times, festivals (without "day"), night
at 6pm, at noon, at Christmas, at night, at the weekend (UK)
on
Days, dates, specific single-day events
on Monday, on 5 May, on Christmas Day, on my birthday
in
Months, years, seasons, centuries, parts of the day
in July, in 2027, in summer, in the 21st century, in the morning
💡
The "big to small" trick works here too
Just like prepositions of place, think from the smallest, most precise unit to the largest: "at" for an exact point (6pm), "on" for a specific day (Monday), "in" for a longer stretch of time (July). "At 6pm, on Monday, in July."
4. More Prepositions of Time
Preposition
Meaning
Example
before / after
Earlier or later than a point
Arrive before 9am. We left after the meeting.
by
No later than a deadline
Submit the form by Friday.
until / till
Up to a point in time, then stopping
I'll wait until 5pm.
from...to / from...until
A defined start and end point
Open from 9am to 5pm.
within
Before the end of a period
We'll reply within 24 hours.
⚠️
by vs until
These are commonly confused. "By Friday" means the action must be completed at some point before or on Friday. "Until Friday" means a situation continues right up to Friday and then stops. "Submit by Friday" (one-time deadline) vs "The offer is valid until Friday" (continues, then ends).
5. for, since and during
Preposition
Use
Example
for
A length or duration of time
I've lived here for five years.
since
A specific starting point in time
I've lived here since 2019.
during
At some point within a period (not the whole duration)
She called during the meeting.
6. Common Mistakes
❌ Incorrect
✅ Correct
Why
I was born in Monday.
I was born on Monday.
Days of the week take "on," not "in."
The meeting is on 6pm.
The meeting is at 6pm.
Clock times take "at," not "on."
I'll see you in the weekend.
I'll see you at the weekend. (UK) / on the weekend. (US)
British English uses "at the weekend"; American English uses "on the weekend."
I've worked here since five years.
I've worked here for five years.
"Since" needs a starting point, not a duration — use "for" with a length of time.
Finish it until Friday.
Finish it by Friday.
A one-time deadline needs "by," not "until."
7. Exercises
A. Gap Fill — Complete with the correct preposition of time (10 questions)
1. The film starts ___ 8pm.
2. I was born ___ 14 March.
3. We're going on holiday ___ July.
4. I haven't seen her ___ Christmas.
5. Please finish the report ___ Friday.
6. I've been waiting ___ two hours.
7. The shop is open ___ 9am ___ 6pm.
8. She called me ___ the meeting.
9. I'll wait ___ 5pm, then I'm leaving.
10. We'll get back to you ___ 48 hours.
Show Answers (A)
1. at 2. on 3. in 4. since 5. by 6. for 7. from, to 8. during 9. until 10. within
B. Multiple Choice (8 questions)
1. I'll see you ___ Monday. (a) in (b) on
2. The train leaves ___ 7pm. (a) at (b) on
3. She was born ___ 1998. (a) in (b) on
4. We open ___ the morning. (a) in (b) at
5. I've lived here ___ 2015. (a) for (b) since
6. I've lived here ___ ten years. (a) for (b) since
7. Finish the exam ___ 11am. (a) by (b) until
8. The offer is valid ___ Sunday. (a) by (b) until
Show Answers (B)
1.b 2.a 3.a 4.a 5.b 6.a 7.a 8.b
C. Error Correction (8 questions)
1. I was born in Monday.
2. The meeting is on 6pm.
3. I've worked here since five years.
4. Finish it until Friday.
5. I'll see you in the weekend. (British English)
6. She called during two hours.
7. The shop is open since 9am to 6pm.
8. I'll wait by 5pm, then I'm leaving.
Show Answers (C)
1. I was born on Monday. 2. The meeting is at 6pm. 3. I've worked here for five years. 4. Finish it by Friday. 5. I'll see you at the weekend. 6. She called during the meeting. / She waited for two hours. 7. The shop is open from 9am to 6pm. 8. I'll wait until 5pm, then I'm leaving.
D. Freer Practice — Write Your Own Sentences (3 tasks)
1. Write a sentence about your daily routine using 'at' with a clock time.
2. Write a sentence using 'since' and a sentence using 'for' about the same situation.
3. Write a sentence using 'by' to describe a deadline.
Show Answers (D)
Model answers will vary. Examples: 1. "I usually wake up at 7am." 2. "I've studied English since 2020." / "I've studied English for six years." 3. "Please send the file by Friday."
8. Mini Quiz
9. Exam Focus — Cambridge, IELTS, SELT
Exam
How This Is Tested
Sample Question
Cambridge A2 Key / B1 Preliminary
in/on/at for time in Reading and Use of English gap-fills.
"The party starts ___ 7pm." (at)
Cambridge B2 First
by/until and for/since precision in Use of English Part 2 and Writing.
"Submit the application ___ Friday." (by)
IELTS Writing & Speaking
Accurate for/since use is essential when describing duration in both Speaking and Writing.
"I have worked in this field for eight years."
Trinity GESE/ISE (SELT)
Describing daily routines and personal history accurately using time prepositions.
"What time do you usually start work?"
10. Frequently Asked Questions
'At' is for precise times (at 6pm); 'on' is for days and dates (on Monday); 'in' is for longer periods like months, years and seasons (in July).
'By' means no later than a deadline for a one-time action ('submit by Friday'); 'until' means a situation continues up to a point and then stops ('open until Friday').
'For' describes a duration or length of time ('for five years'); 'since' describes a specific starting point ('since 2019').
'During' describes something happening at some point within a period ('she called during the meeting'); 'for' describes the full length of time something lasted.
Both are correct: British English typically uses 'at the weekend,' while American English typically uses 'on the weekend.'
Yes — describing your daily routine, work schedule and personal history naturally requires accurate time prepositions in Trinity GESE/ISE speaking tests.
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