Blog about English
Using prepositions to express time, dates, duration and frequency.
English uses prepositions to express relationships between events and points, periods, or durations of time.
The most common time prepositions are at, on, in, for, since, by, until, during, and from ... to.
At is commonly used before exact times and specific points on a clock.
For example, at 6 o’clock, at noon, and at midnight.
At occurs in a number of conventional expressions referring to fixed times or periods.
For example, at night, at the weekend, at lunchtime, and at the moment.
On is used with days of the week and specific days.
For example, on Monday, on Friday, and on my birthday.
On is used before specific calendar dates.
For example, on 15 August, on August 15, and on 1 January 2027.
In is used with months, years, seasons, and other relatively long periods.
For example, in July, in 2026, and in winter.
In is commonly used with morning, afternoon, and evening.
For example, in the morning, in the afternoon, and in the evening.
At is normally used with night rather than in when referring generally to the nighttime period.
For example, I work at night and We arrived at night.
On is used before a specific day even when the day is followed by a part-of-day expression.
For example, on Monday morning, on Friday evening, and on Sunday afternoon.
Certain expressions of time normally occur without a preposition.
For example, last week, next year, this morning, every Monday, and today.
Yesterday, today, and tomorrow normally occur without at, on, or in when used as basic time expressions.
For example, I saw him yesterday and We will leave tomorrow.
For expresses the length of time that an action or situation continues.
For example, I waited for two hours and She has lived here for ten years.
Since introduces the point in time from which a situation has continued.
For example, I have worked here since 2020 and She has been waiting since Monday.
For expresses duration, while since identifies the starting point of the duration.
For example, I have lived here for five years versus I have lived here since 2021.
By indicates a deadline or the latest time by which something happens.
For example, Please finish the report by Friday.
By can indicate that an action will be completed no later than a specified future time.
For example, I will have finished the work by six o’clock.
Until indicates the endpoint up to which an action or state continues.
For example, We waited until midnight and Stay here until I return.
By describes a deadline by which something happens, while until describes a situation that continues up to a time.
For example, Finish it by Friday differs from Stay here until Friday.
During identifies the period in which an event occurs.
For example, We met during the summer and Nobody spoke during the meeting.
During is a preposition followed by a noun phrase, while while is a conjunction followed by a clause.
For example, during the meeting contrasts with while we were meeting.
From ... to expresses the beginning and end of a time period.
For example, The office is open from nine to five.
From ... until emphasizes the starting point and endpoint of a continuing period.
For example, I will be here from Monday until Friday.
Between ... and identifies the limits of a period or point within a range of time.
For example, The shop is open between 9 and 6.
Within indicates that something happens before a specified period has elapsed.
For example, Please reply within seven days.
Ago indicates that an event happened a specified amount of time before the present or another reference point.
For example, I saw her two days ago.
In can indicate how long it will be before something happens in the future.
For example, The train leaves in ten minutes.
In can indicate the point after which an event will happen, while within indicates that something will happen no later than the end of a specified period.
For example, I will call you in ten minutes means approximately ten minutes from now, while I will call you within ten minutes means at any point before ten minutes have passed.
Throughout indicates that something continues during all or nearly all of a specified period.
For example, It rained throughout the night and She remained calm throughout the interview.
Over can describe something happening throughout or repeatedly during a period, while during simply identifies the period in which something occurs.
For example, We discussed the issue over the weekend and We discussed it during the meeting.
At can be used with beginning, end, start, and similar points within a period.
For example, at the beginning of the year, at the end of the meeting, and at the start of the week.
By the end of identifies a deadline within a larger period.
For example, We will have completed the project by the end of the month.
Different varieties of English commonly use at the weekend or on the weekend.
At the weekend is especially common in British English, while on the weekend is especially common in American English.
In time means early enough to meet a required moment or avoid being too late, while on time means at the scheduled or expected time.
For example, We arrived in time for dinner differs from The train arrived on time.
Ahead of time means earlier than the expected or scheduled time.
For example, We finished the project ahead of time.
Choose the time preposition according to whether the expression refers to a point, day, period, duration, starting point, deadline, or endpoint.
Common mistakes include using in with exact times, using on with years, confusing for and since, confusing by and until, using during before a finite clause, and adding unnecessary prepositions before yesterday or tomorrow.