English grammar

Prepositions of time: rules and examples

Prepositions of time say when something happens or how long it lasts. Use at for exact times (at 6.30), on for days and dates (on Friday, on 26 January) and in for longer periods (in May, in the 1990s). For length and limits, use for with a period (for two years), since with a starting point (since 2020), by for a deadline (by Monday) and until for an end point (until 5 p.m.).

Example

When and how long

  • When: The exam starts at 9 a.m. on Saturday.
  • How long: I have been preparing for three months, since August.
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At, on and in: the full chart

Think of the time getting longer: at for a point, on for a day, in for anything longer.

PrepositionUsed forExamples
atClock times and exact pointsat 7.15, at noon, at midnight, at sunrise
atFestival periods, the weekend (British) and nightat Eid, at Christmas, at the weekend, at night
atFixed phrasesat the moment, at the same time, at the end of the month
onDays, dates and special dayson Tuesday, on 15 August, on my birthday, on Christmas Day
onA day plus part of the dayon Monday morning, on Friday night
inParts of the dayin the morning, in the afternoon, in the evening
inMonths, seasons, years, decades, centuriesin March, in the monsoon, in 2019, in the 1980s, in the 21st century
inTime from now until something happensThe results will be out in two weeks.

Words that need no preposition

Don't use at, on or in before this, next, last, every, today, tomorrow, yesterday, tonight or the day after tomorrow: "We leave next Tuesday", "I saw her last week".

Note the difference between "at night" (during any night, in general) and "in the night" (during one particular night): "I woke up twice in the night."

Prepositions for duration and limits

Most errors come from mixing up these pairs.

PairThe differenceExample
for or sinceFor with a length of time; since with a starting pointfor six months; since January
for or duringFor says how long; during says within which periodI slept for two hours during the flight.
by or untilBy is a deadline; until means something continues up to that timePay by Friday. The office is open until 6.
in or withinIn often means at the end of; within means before the end ofI'll reply in two days. Reply within two days.
ago or beforeAgo counts back from now; before counts back from another past timeShe left two years ago. She had left two years before.
from ... to or between ... andBoth give a start and end pointfrom 2010 to 2020; between 2010 and 2020

Time phrases for IELTS Task 1

Charts with dates need these phrases in nearly every paragraph.

PhraseExample
in + year or decadeExports peaked in 2008. Car ownership grew in the 1990s.
between ... andSales doubled between 2000 and 2010.
from ... toPrices rose steadily from 2015 to 2020.
over the periodOver the period, the number of visitors tripled.
throughout the periodCoal remained the main source throughout the period.
by + future or past yearThe figure is expected to reach 50% by 2040.
at the beginning or end ofAt the end of the period, rail was the most popular option.

Common mistakes

  • Wrong: I will call you in the evening of Monday.

    Right: I will call you on Monday evening.

    A day plus part of the day takes on.

  • Wrong: She has been ill from last week.

    Right: She has been ill since last week.

    A starting point continuing up to now takes since.

  • Wrong: I will come after ten minutes.

    Right: I will come in ten minutes.

    For time from now until something happens, use in.

  • Wrong: I studied during three hours last night.

    Right: I studied for three hours last night.

    For says how long. During needs a period such as during the night.

  • Wrong: He moved to Toronto before two years.

    Right: He moved to Toronto two years ago.

    Ago counts back from now, and it comes after the period.

Using this in IELTS and PTE

Every IELTS Writing Task 1 answer with dates depends on these prepositions: "in 2010", "between 2010 and 2020", "over the period", "by 2030". In IELTS Speaking Part 1 and 2, you talk about routines and past events ("on weekdays", "at the weekend", "two years ago"). In PTE Describe Image and Retell Lecture, accurate time phrases make your description of trends easier to follow.

5 questions

Exercise

Try each one, then open it to check your answer.

  1. 1. Complete this: "We usually visit my grandparents ___ Eid."

    at

    Festival periods take at.

  2. 2. Complete this: "The library is closed ___ Sunday mornings."

    on

    A day plus part of the day takes on.

  3. 3. By or until? "I'll wait here ___ you come back."

    until

    The waiting continues up to that time.

  4. 4. For or during? "Nobody spoke ___ the presentation."

    during

    It refers to within the period of the presentation, not a length of time.

  5. 5. Correct this: "The number of cars rose on 2015."

    The number of cars rose in 2015.

    Years take in.

Frequently asked questions

What is the difference between in and within?+

In two weeks usually means at the end of two weeks from now. Within two weeks means at any time before those two weeks end.

At night or in the night?+

At night means during the night in general: "I can't sleep at night." In the night refers to a particular night: "The baby woke up in the night."

From or since?+

Since goes with perfect tenses and a starting point up to now: "I have lived here since 2020." From needs an end point or a future start: "from Monday to Friday", "from next week".

Is it at the weekend or on the weekend?+

At the weekend is British English and on the weekend is American English. Both are correct; choose one and stay consistent.

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