Since and For: Rules, Examples and Practice

Use since for the starting point of a period and for for its length. Compare “since Monday” with “for three days.” When the situation continues now, a present perfect form often connects that past beginning with the present.

Starting point or duration?

Question	Choice	Examples
When did it start?	since	since noon; since 2022; since we met
How long?	for	for ten minutes; for six months; for years

A starting point identifies a place on a timeline. A duration measures the distance between two points. The same situation can be described both ways: if your class began at nine and it is now eleven, you have been in class since nine, or for two hours.

Maya has lived here since 2021.

💡 2021 identifies the beginning; the situation continues now.

Maya has lived here for five years.

💡 Five years tells us the duration.

We have been waiting for twenty minutes.

💡 The continuous form emphasizes the ongoing activity.

Choose the tense from the meaning

Neither word chooses the whole verb tense for you. For can describe a finished visit: “We stayed for four nights.” It can also describe a future plan: “We will stay for four nights.” For a state continuing now, use a suitable present perfect form: “I have known Lina for years.” Know normally uses the simple form rather than a continuous form.

Since can be followed by a time expression or a clause: “since the move” and “since we moved.” In a continuing-present example, the clause naming the starting event often uses the past simple. Past perfect can describe a period leading up to a later past moment: “By Friday, they had worked together for a week.”

Since can also give a reason

In “Since the café is closed, let's meet elsewhere,” since means because. That is a different use, so the starting-point rule does not apply. Read the whole sentence before deciding what since means.

Common mistakes

❌ I have studied here since six months.

✅ I have studied here for six months.

Six months is a length, not a starting point.

❌ She has worked here for 2020.

✅ She has worked here since 2020.

2020 identifies when the period began.

Practice: 12 questions

Try all twelve before reading the answers. Use the context in each sentence, not just a single signal word.

1. I have worked here ___ 2020. Choose since or for.

2. We have waited ___ forty minutes. Choose since or for.

3. Nora has known Amir ___ primary school. Choose since or for.

4. They stayed in Lisbon ___ three nights last summer. Choose since or for.

5. I will borrow the bike ___ an hour. Choose since or for.

6. She has been studying ___ breakfast. Choose since or for.

7. We have lived in this flat ___ two years. Choose since or for.

8. The shop has been closed ___ Monday. Choose since or for.

9. I have felt better ___ I changed my routine. Choose since or for.

10. He had been driving ___ six hours when he stopped. Choose since or for.

11. Rewrite using a duration: “They have been here since noon.” It is now 3 p.m.

12. Does since express time or reason in “Since the road is flooded, take the train”?

Answers and explanations

1. since

💡 2020 is a starting point.

2. for

💡 Forty minutes measures a duration.

3. since

💡 Primary school names the period when the relationship began.

4. for

💡 The visit lasted three nights; for also works with the past simple.

5. for

💡 An hour is the length of a future borrowing period.

6. since

💡 Breakfast is the starting event.

7. for

💡 Two years tells us how long.

8. since

💡 Monday marks the beginning.

9. since

💡 The clause identifies the event that began the change.

10. for

💡 Six hours measures the period before a later past event.

11. They have been here for three hours.

💡 The interval from noon to 3 p.m. is three hours.

12. Reason

💡 Since means because; it explains the travel advice.

Can I use for with the past simple?

Yes. “I worked there for a month” describes the length of a finished period.

Can since be followed by a sentence?

Yes. “I have been happier since I joined the club” uses a clause to name the starting event.

Keep learning

Review the present perfect, compare the present perfect and past simple, or study prepositions.

Grammar reference: Cambridge on since, for and ago. The lesson explanations and practice questions are original.

Practice in the 30 Days English Challenge: Day 12: To, For, In, On and At: Everyday Prepositions · Day 13: For, Since, During and While: Say When and How Long