How to Use ON, IN, AT, FOR in English — The Ultimate Grammar Guide

🔍 What Are Prepositions? (English Grammar Prepositions)

Prepositions are small words that show the relationship between two parts of a sentence.
They often relate to time, place, or duration.

The four prepositions in this lesson—ON, FOR, IN, AT—are extremely important in daily English and appear often in English exams like IELTS and TOEFL. Using them correctly will help learners speak more naturally and confidently.


📌 Preposition “ON” — How to Use It ( Preposition ON Examples)

We use ON for specific days and dates, and some special expressions.

✔ Examples:

  • on holiday

  • on Friday

  • on my birthday

📘 Explanation:

  • Use on + a specific day

  • Use on for dates

  • Use on for special personal days (birthday, anniversary…)

More Examples:

  • I will travel on Monday.

  • She called me on my birthday.

  • We are going to the beach on the weekend (US English).


Preposition “FOR” — Duration ( Preposition FOR Duration Examples)

Use FOR when talking about how long something lasts.

✔ Examples:

  • for five days

  • for 3 months

  • for a long time

📘 Explanation:

  • “For” is used with periods of time.

  • You can use it in all tenses.

More Examples:

  • I studied English for two years.

  • She stayed in Paris for a week.

  • They waited for a long time.


🕰 Preposition “IN” — Months, Seasons, and Parts of the Day ( Preposition IN Time Examples)

Use IN for months, years, seasons, and parts of the day.

✔ Examples:

  • in the morning

  • in July

More Examples:

  • I wake up early in the morning.

  • We will travel in summer.

  • The school opens in September.


📍 Preposition “AT” — Exact Time and Specific Places ( Preposition AT Examples)

Use AT for exact time, specific places, and some fixed expressions.

✔ Examples:

  • at 3 o’clock

  • at the weekend

  • at the station

More Examples:

  • The train arrives at 6:15.

  • I will meet you at the station.

  • She studies at night.


Summary Table ( Prepositions Table ON IN AT FOR)

PrepositionUsed For
ONDays, dates, special occasions
FORDuration / period of time
INMonths, years, parts of day, seasons
ATExact time, specific places, fixed expressions