Prepositions of Time

Mastering when to use prepositions with time expressions is fundamental to clear English communication. This A1–B1 lesson covers prepositions of time — words like at, in, on, for, since, during, by, and until that tell us when something happens, how long it lasts, or by when it must be done. To use them correctly, you need to understand 2 core time questions and 10 key prepositions:

• When? (point or period in time): at, in, on, before, after
• How long? (duration): for, since, during
• By when? (deadline or continuation): by, until
• Other essential prepositions: ago, within, from...to

The biggest challenges? Three major traps catch even intermediate learners: the zero preposition rule (no preposition with last, next, this, every, today, tomorrow), for vs since vs during confusion, and by vs until mix-ups. We'll tackle these head-on with dedicated sections and clear decision guides.

Important Note: This lesson covers TIME prepositions only. If you're looking for place prepositions (at the station, in London, on the table), see Prepositions of Place.

At, In, On — The 3 Core Rules

The three most important prepositions of time are at, in, and on. Each has specific uses that you must learn to distinguish clearly.

When to Use AT

Use at for specific times and precise moments — think of "at" as marking a point on a timeline.

Key concept: At treats a time as a specific point rather than a period. When you say "I'll meet you at 3pm," you're focusing on that exact moment in time.

When to Use IN

Use in for longer periods and parts of the day — think of "in" as being within a span of time.

Key concept: In emphasizes being within a period of time. "In March" means at some point during the entire month. "In the morning" covers the whole morning period.

Exception: We say "at night" (not "in night"), but "in the night" when referring to a specific night (often implying you woke up): "I heard a noise in the night."

When to Use ON

Use on for specific days and dates — think of "on" as landing on a particular day in the calendar.

Key concept: On indicates a specific day on the calendar. "On Monday" pinpoints that particular day, not the whole week.

At vs In vs On: Quick Comparison

Common contrasts:

• The meeting is at 10 o'clock. (specific time)
• The meeting is in the morning. (general period)
• The meeting is on Tuesday. (specific day)

👉 Practice At, In, On: Core Rules →

At, In, On — Tricky Cases & ⚠️ The Zero Preposition Rule

Beyond the basic rules, there are special cases and a crucial rule that trips up many learners: when NOT to use a preposition at all.

Special Time Expressions with AT

Certain time expressions always use at, even if they seem like longer periods:

Festival Period vs Festival Day:

• At Christmas = the festival period (around Christmas time)
• On Christmas Day = December 25th specifically

Examples:

• We exchange gifts at Christmas. (the whole season)
• We exchange gifts on Christmas Day. (the specific date)

Day + Part of Day: Use ON

When you combine a day with a part of the day, use on (not "in"):

• ✅ I have a meeting on Monday morning.
• ❌ I have a meeting in Monday morning. (incorrect)
• ✅ The concert is on Saturday evening.
• ❌ The concert is in Saturday evening. (incorrect)

⚠️ The Zero Preposition Rule

This is the #1 error zone for learners at all levels. Certain time words never take a preposition — using one sounds very unnatural.

NO PREPOSITION with these words:

Why no preposition? These words already contain time information — they function as adverbs of time. Adding a preposition is redundant and grammatically wrong.

Examples:

• ✅ I went to the cinema last Saturday.
• ❌ I went to the cinema on last Saturday. (incorrect)
• ✅ We're having a party next week.
• ❌ We're having a party in next week. (incorrect)
• ✅ Are you doing anything tomorrow?
• ❌ Are you doing anything on tomorrow? (incorrect)

At Night vs In the Night

This subtle distinction confuses many learners:

Common pattern: "In the night" often appears with past simple to describe something that happened during one particular night.

👉 Practice Tricky Cases & Zero Preposition →

For, Since & During — Duration Prepositions

These three prepositions all relate to time duration, but they're used in completely different ways. Mixing them up is error zone #2.

FOR — Duration / Length of Time

Use for to say how long something lasts or has lasted. For answers the question "How long?"

Examples:

• I have lived here for ten years. (How long? Ten years.)
• She slept for twelve hours after the long flight.
• We've been friends for a very long time.

Tense note: For is commonly used with present perfect (have lived for...) or past simple (lived for...).

SINCE — Starting Point

Use since to say when something started. Since marks the beginning point and indicates the situation continues until now. Since answers the question "Since when?"

Examples:

• I have lived here since 2015. (When did it start? 2015. It continues now.)
• She has worked at this company since January.
• We haven't spoken since the argument.

Tense note: Since is almost always used with present perfect (have lived since...), never with past simple.

Connection to Present Perfect: For and since are commonly taught together with the present perfect tense, as they often describe situations that started in the past and continue to the present. If you're not familiar with present perfect, see Present Perfect to understand how these prepositions work with that tense.

DURING — Within a Named Period

Use during to say when something happened within a specific period or event. During is followed by a noun (not a length of time).

Examples:

• Please don't use your phone during the lesson.
• I fell asleep during the film.
• It rained a lot during the night.

⚠️ Don't Confuse: For vs Since vs During

This is the most common mistake with duration prepositions. Here's how to decide:

Common errors:

During vs While

Don't confuse "during" (preposition) with "while" (conjunction):

• During + noun: during the film
• While + clause: while I was watching the film

Both mean "when something happened," but the grammar is different:

• ✅ I fell asleep during the film. (during + noun)
• ✅ I fell asleep while I was watching the film. (while + clause)
• ❌ I fell asleep during I was watching the film. (incorrect — "during" needs a noun, not a clause)

In (Future Time) vs For (Duration)

Another common confusion: "in two weeks" ≠ "for two weeks"

Examples:

• She'll arrive in half an hour. (= half an hour from now)
• She stayed for half an hour. (= the visit lasted 30 minutes)

👉 Practice For, Since & During →

By, Until, Before, After & Other Time Prepositions

These prepositions help you express deadlines, continuation, sequence, and time ranges.

⚠️ By vs Until — The Deadline Trap

This is error zone #3. Both "by" and "until" refer to a future time point, but their meanings are completely different.

BY — Deadline for Completion

By means "no later than" — the action must be completed at or before that time.

• The report must be finished by Friday. (= on Friday or earlier)
• Please arrive by 9am. (= at 9am or before)

Key pattern: By is used for one-time actions with a deadline. The action happens BEFORE or AT that time, not continuously.

Examples:

• You must submit your application by 5pm on Friday. (deadline)
• I need to finish this by tomorrow morning.
• Can you send me the file by the end of the day?

UNTIL (or TILL) — Continuation Up to a Point

Until means "up to a time or event" — the action or state continues up to that point and then stops.

• The shop stays open until 9pm. (= it's open continuously from opening time up to 9pm)
• I'll wait here until you come back. (= I'll continue waiting; I'll stop when you return)

Key pattern: Until is used for continuing actions or states. The situation continues UP TO that time.

Examples:

• We won't leave until the rain stops. (we'll stay; we'll leave when it stops)
• The library is open until midnight.
• I won't be home until late tonight. (I'll be away continuously until late)

How to Decide: By or Until?

Common errors:

Memory trick:

• BY = Be done Before You run out of time (deadline)
• UNTIL = Continues un-til it stops

BEFORE & AFTER — Sequence

Before and after show the order of events in time.

Before and after as prepositions vs conjunctions:

• Preposition + noun: before breakfast, after dinner
• Conjunction + clause: before you leave, after we finish

Both patterns are correct:

• ✅ I'll call you before lunch. (preposition + noun)
• ✅ I'll call you before I have lunch. (conjunction + clause)

AGO — Looking Back from Now

Ago means "back from now" — it measures time backwards from the present moment.

Examples:

• I graduated three years ago. (= three years before now)
• The train left ten minutes ago.
• She moved to London five months ago.

Critical tense rule: Ago is ALWAYS used with past simple, never with present perfect.

• ✅ I moved here three years ago. (past simple)
• ❌ I have moved here three years ago. (incorrect — can't use present perfect with "ago")

Don't confuse ago with since:

• Ago (past simple): I started this job six months ago. (= six months back from now)
• Since (present perfect): I have worked here since June. (= from June until now)

For more on past simple usage, see Past Simple.

WITHIN — Time Limits

Within means "in no more than" — it sets a maximum time limit.

• You must reply within 48 hours. (= no more than 48 hours)
• The doctor will see you within 30 minutes. (= in 30 minutes or less)
• You must check in within 30 minutes of arrival.

Within vs In:

• Within = maximum time limit (could be less)
• In (future) = at that point in the future (exactly)

Examples:

• The taxi will arrive in 10 minutes. (= 10 minutes from now)
• The taxi will arrive within 10 minutes. (= in 10 minutes or less)

FROM...TO / FROM...UNTIL — Time Ranges

Use from...to (or from...until) to show a time range with a clear start and end.

Examples:

• The café is open from 7am to 10pm every day.
• I lived in Paris from 2010 to 2018.
• The museum is closed from Monday until Wednesday for repairs.

To vs Until: Both are acceptable in time ranges. "To" is slightly more common; "until" emphasizes continuation up to the end point. In practice, they're interchangeable in this context.

👉 Practice By, Until, Before, After →

Common Mistakes to Avoid

These errors are specific to time prepositions — and very common among learners at all levels.

Quick Summary

Decision Flowchart 1: Choosing At, In, or On

What type of time expression is it?

→ Clock time (3pm, midnight)? → Use AT
→ Specific day (Monday, Christmas Day)? → Use ON
→ Month/Year/Season (March, 2024, summer)? → Use IN
→ Part of day (morning, afternoon, evening)? → Use IN
  Exception: "night" → Use AT (at night)

Special cases:
→ Festival period (Christmas, Easter)? → Use AT
→ Last/Next/This/Every/Today/Tomorrow? → NO PREPOSITION

Decision Flowchart 2: Choosing For, Since, or During

What type of information do you have?

→ A LENGTH of time (3 hours, 2 years, a long time)? → Use FOR
→ A STARTING POINT (2020, Monday, since I moved)? → Use SINCE
→ A NAMED PERIOD or event (the meeting, summer, the night)? → Use DURING

Decision Flowchart 3: By vs Until

What is the nature of the action?

→ One-time action with a DEADLINE (must be completed by that time)? → Use BY
→ Continuing action/state UP TO a point (continues until that time)? → Use UNTIL

Core Time Prepositions Table

Zero Preposition — Quick Reference

NO preposition with:

• Last: last week, last Monday, last year
• Next: next week, next Friday, next month
• This: this week, this Friday, this summer
• Every: every day, every Monday, every year
• Today, tomorrow, yesterday, tonight

Practice Tips

1. Create a time diary: Write 10 sentences about your daily routine using at, in, and on (I wake up at 7am. I have lunch at noon. I go to the gym in the evening. I have a meeting on Monday.).

2. Master the zero preposition rule: Make flashcards for "last/next/this/every + time word" and practice saying them WITHOUT a preposition. This is the most common mistake — drilling it will save you from errors.

3. For vs Since drill: Write 10 sentences about your life experiences — 5 with "for" (I have lived here for 3 years) and 5 with "since" (I have lived here since 2021). Pay attention to the difference between length and starting point.

4. By vs Until distinction: Find 5 real-life deadlines (submit homework by Friday, finish reading by tomorrow) and 5 continuing situations (the library is open until 10pm, I'll wait until you arrive). Notice how "by" is for one-time completions and "until" is for ongoing states.

5. Timeline exercise: Draw a timeline and mark events with different prepositions (at, on, in, since, ago, before, after). Visualizing time helps cement the distinctions.

6. Spot the preposition: When reading or watching TV in English, pay attention to time prepositions. Notice which ones native speakers use with different time expressions. Keep a list of new patterns you discover.

Practice All Exercises

Ready to practice everything you've learned? These prepositions of time exercises are available online as multiple choice questions with answers, plus printable PDF worksheets for offline practice. Work through the sets in order — they follow the same progression as this lesson:

👉 Practice Mixed Review → for a comprehensive test of all time prepositions!