Overview
'Since' is used with a specific point in time to show when something started (since 2010, since Monday). 'For' is used with a duration to show how long something has lasted (for two years, for ages). Both are most commonly used with the present perfect tense.
Since — Point in Time
- Since + a specific point when something started.
- YearI have lived here since 2015.
- TimeShe has been waiting since 3 o'clock.
- EventHe hasn't eaten since breakfast.
- ClauseI've known her since I was a child.
For — Duration
- For + a period of time (how long).
- HoursI have lived here for nine years.
- DaysShe has been waiting for two hours.
- LongHe hasn't eaten for a long time.
- AgesWe haven't spoken for ages.
Quick Test
- Ask: From when? → use since.
- Ask: How long? → use for.
- ✓I've waited since noon / for three hours.
- ✗I've waited since three hours / for noon.
When to use
Present perfect
I have studied English for five years.
Duration
She has worked here since January.
Formal writing
We have not received payment since the invoice date.
Conversation
I haven't seen him for ages!