For and Since for Time

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for + period

A period is a duration of time, for example: 5 minutes, 2 weeks, 6 years. For means "from the beginning of the period until the end of the period." For can be used with all tenses.

since + point

A point is a precise moment in time, for example: 9 o'clock, 1st January, Monday. Since means "from a point in the past until now." Since is normally used with perfect tenses.

for
a period
(from start to end)
>===< since
a point
(up to now)
x===>|
for 20 minutes
for three days
for 6 months
for 4 years
for 2 centuries
for a long time
for ever
etc since 9am
since Monday
since January
since 1997
since 1500
since I left school
since the beginning of time
etc
all tenses perfect tenses only

For can be used with all tenses. Here are a few examples:


Both for and since also have other meanings, with no reference to time. Here are some examples:
This is for you.
Is this the train for London?
Since you ask, I'll say yes.
Since he didn't study he didn't pass the exam.


They study for two hours every day.
They are studying for three hours today.
He has lived in Bangkok for a long time.
He has been living in Paris for three months.
I worked at that bank for five years.
Will the universe continue for ever?
For is NOT used with "all day", "all the time" etc.

I was there all day. (not *for all day)
Since is normally used with perfect tenses:

He has been here since 9am.
He has been working since he arrived.
I had lived in New York since my childhood.
Since can also be used in the structure "It is [period] since...":

It is a year since I saw her.
How long is it since you got married?
Now c