English UsageGrammar guide
Since vs. For
Since and for can both locate a situation in time, but they answer different questions. Since introduces the starting point from which a situation continues; for introduces a duration or period of time.
Use since with a starting point and for with a duration: since 2020, for three years.
Key details
For Roleduration or period of time
Since Rolestarting point in time
Termssince, for
Choose the right form
| Choice | Use it when | Example |
|---|---|---|
| since | a starting point | since Monday |
| for | a duration | for three days |
Further guidance
Tense Boundary
The tense depends on the whole sentence; the since/for distinction itself is point versus period.
Time Boundary
Do not use since with a duration such as three hours; use for for the length of time.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- For or since? (opens in a new tab)Cambridge Dictionary · For with periods of time and since with starting points