"Since" vs "For": The Time Rule Every Exam Student Needs
Since vs for in present perfect tense — the difference between a starting point and a duration, with examples and exam tips.
I have lived here since 2015.
I have lived here for eight years.
Both sentences describe the same situation — you started living here in 2015 and still live here now. But the time expressions are different. “Since 2015” points to a starting moment. “For eight years” describes a length of time.
This is the core difference between “since” and “for,” and it is one of the most tested grammar points in English exams worldwide.
“Since” answers the question: “From when?”
It marks the exact point in time when something began. It is always used with a perfect tense (present perfect, past perfect, etc.).
since + a specific point in time
I have known her since 2010.
She has been waiting since morning.
They have lived in Delhi since January.
He has worked here since he graduated.
We haven’t met since last summer.
Since I was a child, I have loved music.
| Type | Examples |
|---|---|
| A year | since 2020 |
| A month | since March |
| A day | since Monday |
| A specific date | since 15th August |
| A specific moment | since 5 o’clock |
| A life stage | since childhood |
| A past event | since I arrived, since the accident |
| A clause (subject + verb) | since she left, since we moved here |
The key: “since” always refers to a specific, identifiable moment when something began.
“For” answers the question: “How long?”
It describes the total length of time something has lasted. Unlike “since,” “for” can be used with any tense — not just perfect tenses.
for + a period of time
I have lived here for eight years.
She has been studying for three hours.
They have waited for a long time.
He has been absent for two weeks.
I stayed in London for two weeks. (past simple)
She will be away for a month. (future)
He works for eight hours every day. (present simple)
“For” is not limited to perfect tenses. It works anywhere you need to express duration.
| Type | Examples |
|---|---|
| Hours / minutes | for two hours, for thirty minutes |
| Days / weeks | for five days, for three weeks |
| Months / years | for six months, for ten years |
| General periods | for a long time, for ages, for a while |
| Specific amounts | for 45 minutes, for 2½ years |
Compare these two sentences:
She has worked here since 2018.
She has worked here for six years.
Both describe the same reality. The difference is perspective:
- “Since 2018” focuses on the starting point — the moment she began.
- “For six years” focuses on the duration — the total time elapsed.
You can often use both to describe the same situation:
I have known him since college. = I have known him for many years.
She has been ill since Monday. = She has been ill for four days.
Incorrect: I have lived here since three years.
Correct: I have lived here for three years.
“Three years” is a duration, not a starting point. Use “for.”
Incorrect: She has worked here for 2015.
Correct: She has worked here since 2015.
“2015” is a starting point, not a duration. Use “since.”
Incorrect: I have been waiting since a long time.
Correct: I have been waiting for a long time.
“A long time” is a duration. Use “for.”
Incorrect: I am living here since 2020.
Correct: I have been living here since 2020.
“Since” requires a perfect tense. “I am living” is present continuous, not perfect. Use “have been living” (present perfect continuous).
Incorrect: The meeting is for Monday.
Correct: The meeting is on Monday. (if referring to schedule)
Or: I have been busy since Monday. (if referring to duration from a starting point)
“For” with a specific day is not standard when “since” or “on” is meant.
“Since” can also function as a conjunction meaning “because”:
Since you’re here, let’s begin.
I haven’t seen him since he moved to Mumbai.
Since it was raining, we stayed home.
In these sentences, “since” introduces a clause (subject + verb). This is different from the preposition use, where “since” is followed by a noun or time expression.
Context usually makes the meaning clear. “Since 2015” = from that time. “Since you asked” = because you asked.
Choose “since” or “for.”
- I have been studying ______ two hours.
- She has lived in Mumbai ______ 2018.
- They have been friends ______ childhood.
- He has been absent ______ three days.
- We haven’t spoken ______ last month.
- I am working here since five years.
- She has been waiting for 3 o’clock.
- They have known each other since a long time.
- for — “two hours” is a duration
- since — “2018” is a starting point
- since — “childhood” is a starting point in life
- for — “three days” is a duration
- since — “last month” is a starting point
- I have been working here for five years (or “since 2019”) — “since” needs a perfect tense, and “five years” is a duration
- since 3 o’clock — “3 o’clock” is a specific time point, not a duration
- for a long time — “a long time” is a duration, not a starting point
The distinction is simple:
- Since = starting point (a specific moment). Answers: “From when?”
- For = duration (a length of time). Answers: “How long?”
“Since” is always used with a perfect tense. “For” can be used with any tense.
When you see a time expression, ask yourself: “Is this a moment or a length?” If it is a moment (2015, Monday, childhood), use “since.” If it is a length (three years, two hours, a long time), use “for.”
Yes. “For” works with all tenses, including present perfect: “I have lived here for ten years.”
Primarily, yes. “Since” is almost always used with a perfect tense (present perfect, past perfect, present perfect continuous, etc.). Using “since” with simple present or simple past is generally incorrect.
“Incorrect: since three years ago” — This is redundant. “Since” already implies “from that point until now.” Use either “since 2020” or “three years ago,” but not both together.
I have lived here since 2020. (present perfect + since)
I moved here three years ago. (past simple + ago)
Yes. “Since you asked, I’ll tell you” = “Because you asked, I’ll tell you.” This is a different use of “since” — as a conjunction, not a preposition.