For or since? How to talk about how long
Vocalyra teaching team · Last updated:
For and since both answer how long, but they look at time from different angles. For measures a length of time, while since points to the moment something started.
The difference in one line
Use for with a period: for ten minutes, for three years, for a long time. Use since with a starting point: since Monday, since 2020, since I was a child. Both are often followed by the present perfect when the situation continues now.
| For + period | Since + starting point |
|---|---|
| for two hours | since nine o'clock |
| for six months | since April |
| for ages | since we met |
| for a week | since last Tuesday |
| for twenty years | since 2006 |
Which tense goes with them
- Continuing situation: I have lived in Toronto for five years. I have lived in Toronto since 2021.
- Continuing activity: She has been studying since this morning.
- Finished situation: for can go with the simple past. I lived in Rio for two years (and then moved). Since cannot be used this way.
- Future: for also works with the future. We will stay for a week.
Common errors
- I am here since Monday. Correct: I have been here since Monday.
- I have worked here since three years. Correct: for three years.
- I study English for 2022. Correct: I have studied English since 2022.
French depuis, Spanish desde hace or desde, and Portuguese há or desde all combine with the present tense. English needs the present perfect instead, which is why I am here since Monday sounds natural to many learners but is incorrect.
Asking the question
The question form is How long have you ... ? How long have you worked here? You can answer with either word: For six months, or Since March. If you want the start date directly, ask Since when have you worked here? which sounds slightly more direct.
Quick self-check
Complete: I have known her ___ 2015.
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Since.
Complete: We waited ___ forty minutes.
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For.
Correct: He is ill since Friday.
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He has been ill since Friday.
Can you say: I lived in Paris since three years?
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No. Say I lived in Paris for three years (finished) or I have lived in Paris for three years (still true).