Since and For | Use of Since and For

Since and for are very important in English grammar.Since and for often confused students.Here are some tips that will make use of since and for very easy.

The use of FOR

For is used when someone measures the duration – when someone says how long something lasts.

For + a period of time
When we measure a period of time up to the present, present perfect tense is used and we do not use the present tense.

Examples:

I have known Alina for a long time. (Correct)
I know Alina for a long time. (Incorrect)
- - We have lived here for five years. (Correct)
    We live here for five years. (Incorrect)

The present tense with For indicate a period of time that is related to the future.

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

In a nutshell, For Is used with all kind of verbs.

Uses of For
Example sentence	Verb Tense
We exercise for two hours every day.	Present tense
We are exercising for three hours today.	Present continuous
William has lived in Toronto for a long time.	Present perfect
William has been living in New York for four months.	Present perfect continuous
He worked at the gas station for six years.	Past tense
John will be in hospital for at least two weeks.	Future tense

However, we should remember that we don’t use For with these expressions such as all day or all the time.

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

The use of SINCE

Since indicates the starting point of actions, events and states. It informs us when things began.

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

Sonia has been waiting since 7 o’clock.
I have known Clark since March.

We use the present perfect tense and the past perfect tense with since.

He has been here since 3 o’clock and he is getting tired.
Watson had been working since 6 o’clock and he was getting tired.
This structure (It has been + period of time + since) can be used when we use Since.

It has been three months since I last saw Siam.
It has been four years since the last flood.

Since vs. For

It is very important to know when to use FOR and when to use SINCE. So here is the summary of the comparison and the difference between FOR and SINCE.

FOR refers to a specific period (or duration) of time.	SINCE refers to the starting point of a period of time (continues to now).
Sarim has been a doctor for twenty years. (duration = 20 years)	Sarim has been a doctor since 1996. (starting point = 1996)
Alisa has been a mother for seven months.	Alisa has been pregnant since her first child was born.
My sister has lived in France for ten months.	My sister has lived in France since the beginning of May.

We usually use For and Since with the perfect tense – we don’t use these words in the present tense.

Correct	Incorrect
James has learnt French for four years.	James learn French for four years.
We have taught History since last year.	We teach History since last year.
Donald has owned his cat since his dog died.	Donald owns his cat since his dog dies.

For is used in the simple past tense but we can’t use Since in the simple past tense. So Since is only used in the perfect tense.

Correct	Incorrect
He went to Canada for five years.	He went to Canada since 2004.
He studied in Sweden for two months.	He studied in Sweden since two months.
Rock walked his dog for five hours.	Rock walked his cat since five hours.