For - Since

English Grammar

The use of FOR

We use For when we measure the duration – when we say how long something lasts.

For + a period of time
To measure a period of time up to the present, we use the present perfect tense and not the present tense.

I have known her for a long time. (Correct)
I know her for a long time. (Incorrect)
I have lived here for ten years. (Correct)
I live here for ten years. (Correct)

The present tense with For refers to a period of time that extends into the future.

How long are you here for? (Until when)
How long have you been here for? (Since when)

In reality, we can use all verb tenses with For.

Uses of For
Example sentence	Verb Tense
They exercise for two hours every day.	Present tense
They are exercising for three hours today.	Present continuous
He has lived in Moscow for a long time.	Present perfect
He has been living in Turin for three months.	Present perfect continuous
I worked at the service station for five years.	Past tense
He will be in hospital for at least a week.	Future tense

However, we don't use For with expressions such as all day or all the time.

I was there all day. (Correct)
I was there for all day. (Incorrect)

The use of SINCE

Since gives the starting point of actions, events or states. It refers to when things began.

Since + a point in time (in the past), until now.

I've been waiting since 7 o'clock.
I have known him since January.

With since we use the present perfect tense or the past perfect tense.

I have been here since 5 o'clock and I am getting tired.
I had been working since 5 o'clock and I was getting tired.

Since can also be used in the structure It has been + period of time + since.

It has been two months since I last saw her.
It has been three years since the last earthquake.

For vs. Since

Knowing when to use FOR and when to use SINCE is important. Therefore it is useful to look at a summary of the contrast between FOR and SINCE.

FOR to mention a specific period (or duration) of time.	SINCE to mention the starting point of a period of time (continues to now).
I have been a doctor for fifteen years. (duration = 15 years)	I have been a doctor since 1992. (starting point = 1994)
She has been a mother for six months.	She has been pregnant since her first child was born.
My sister has lived in Frankfurt for nine months.	My sister has lived in Frankfurt since the beginning of March.

Both For and Since are most commonly used with the perfect tense - we don't use these expressions in the present tense.

Correct	Incorrect
I have learnt Russian for three years.	I learn Russian for three years.
They have taught geography since last year.	They teach geography since last year.
He has owned his dog since his cat died.	He owns his dog since his cat dies.

While we can use For in the simple past tense we can't use Since in the simple past tense. Since can only be used in the perfect tense.

Correct	Incorrect
She went to Japan for three years.	She went to Japan since 2003.
I studied in New Zealand for one month.	I studied in New Zealand since one month.
He walked his dog for four hours.	He walked his cat since four hours.

It should be remembered that both For and Since have other meanings in English that are not associated with time.

This is for you.
Is this the train for London?
Since you asked, I'll say yes.
Since he didn't study he didn't pass the exam.

Would you like to play a game to practice the difference between For and Since? Then try this Game.

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Last Updated: 04 February 2009

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For - Since

English Grammar

The use of FOR

The use of SINCE

For vs. Since