On / At / In / By – prepositions for time


When referring to TIME –

On – is used for mentioning days and dates.

In – is used for mentioning a time period – week, month, year, age, etc.

At – is used for mentioning the exact time.

By – means – ‘either sometime before or on/at/in’.


EXAMPLES

On .

  • Your interview is  on Monday.
  • We will reach  on the 22nd.
  • My joining is  on 1st August.
  • Let’s meet  on Sunday.

In .

  • I will meet you  in January.
  • They came to India  in 1990.
  • I graduated  in the year 2007.
  • He submitted the report  in the last week of December.

At .

  • The meeting is  at 10 AM.
  • That train arrives  at 9:45 PM.
  • I will start the presentation  at 11 AM sharp.
  • Sunrise is  at 5:05 AM.

By .

  • I will definitely submit the document  by Friday.
  • We are planning to leave  by 9.
  • Please complete this work  by next week.
  • They’re planning to shift  by next year.