How to Use “Since” and “For” in English Correctly

Introduction

Do you ever pause before saying “I have worked here since 2019″ or “I have worked here for five years”? You are not alone. Many English learners mix up these two small but powerful words. Getting them right will make your English sound much more natural and accurate. In this post, we will break down the simple rule, show you plenty of examples, and help you avoid the most common mistakes.

What Is “Since” and “For”?

Both since and for are used to talk about time, but they answer different questions. Since tells us when something started. For tells us how long something lasted or has lasted. Think of since as pointing to a specific starting point, and for as measuring a period of time.

Rules

1. Use “since” with a specific point in time. This can be a date (since 1995), a year (since 2020), a month (since January), a day (since Monday), or an event (since I left school).
2. Use “for” with a duration of time. This can be a number of years (for two years), hours (for three hours), months (for six months), or other time periods (for a long time).
3. Both are commonly used with the present perfect tense (have/has + past participle), but “for” can also be used with other tenses (past simple, future, etc.).
4. “Since” can also introduce a clause (a full sentence with a subject and verb), such as “since I moved here.”
5. “For” is never followed by a clause. It is always followed by a noun phrase or a time expression.

How to Use It

Follow these steps to choose correctly every time:

1. Ask yourself: “Is this a starting point or a duration?”
2. If it is a starting point (year, date, event), use since. Example: I have been a teacher since 2015.
3. If it is a length of time (how many years, hours, months), use for. Example: I have been a teacher for nine years.
4. Check the verb tense. With “since,” the main verb is almost always in the present perfect or present perfect continuous. With “for,” you can use many tenses: I lived there for two years. (past simple) or I will stay for a week. (future)
5. Memorise common time expressions. For “since”: since yesterday, since last week, since 2001, since I was a child. For “for”: for a while, for ages, for ten minutes, for a decade.

Examples in Sentences

• She has worked at this company since 2018.
• They have been married for 25 years.
• I haven’t seen him since last Tuesday.
• We have been waiting for over an hour.
• He has studied English since he was twelve.
• My sister has lived in London for a long time.
• I have known my best friend since primary school.
• The meeting has been going on for three hours.
• She has been feeling tired since she got the flu.
• We have owned this car for five years.

Common Mistakes

1. Mistake: Using “since” with a duration.
   ❌ I have been here since three hours.
   ✅ I have been here for three hours.
2. Mistake: Using “for” with a starting point.
   ❌ She has worked here for 2020.
   ✅ She has worked here since 2020.
3. Mistake: Using “since” with a specific clock time incorrectly.
   ❌ I have been waiting since 10 o’clock for two hours. (This mixes both in one sentence awkwardly.)
   ✅ I have been waiting since 10 o’clock. OR I have been waiting for two hours.
4. Mistake: Forgetting to use present perfect with “since.”
   ❌ I am a doctor since 2010.
   ✅ I have been a doctor since 2010.
5. Mistake: Using “for” before a clause (a full sentence).
   ❌ I have known her for she moved here.
   ✅ I have known her since she moved here.

Quick Summary

• Since = starting point (year, date, event).
• For = duration (length of time).
• Both are often used with present perfect tense.
• “Since” can be followed by a clause; “for” cannot.
• To choose, ask: “Is this a point or a period?”

Practice Exercises

Fill in the blanks with since or for.

1. I have lived in this city _______ 2016.
2. We have been friends _______ more than a decade.
3. She hasn’t eaten anything _______ breakfast.
4. They have been studying _______ three hours straight.
5. He has worked as a chef _______ he graduated from culinary school.

Answers:

1. since
2. for
3. since
4. for
5. since

Conclusion

Mastering the difference between since and for will instantly improve your fluency and accuracy in English. Remember: since points to a start, and for measures a span. Practice with the exercises above, and soon it will become second nature. Keep learning, and don’t be afraid to make mistakes—that is how we grow!

FAQ

1. Can I use “since” with the past simple tense?

Generally, “since” is used with the present perfect or present perfect continuous tense in the main clause. However, in informal English, you might hear sentences like “It’s been two years since I saw him.” This is acceptable, but the structure “It has been two years since I saw him” is grammatically standard.

2. Can I use “for” with the present perfect continuous?

Absolutely. “For” works perfectly with all tenses, including the present perfect continuous. Example: “She has been running for an hour.”

3. What is the difference between “since” and “from”?

“Since” is used to talk about a starting point that continues to the present. “From” is used to describe a starting point without necessarily continuing. For example: “I work from 9 to 5” (a routine), but “I have worked here since 9 o’clock” (still working now).

4. Is it ever correct to say “since two hours”?

No, never. “Since” must be followed by a specific point in time, not a duration. To express a duration, use “for.” So, “since two hours” is always wrong. Say “for two hours” instead.