for and since for Time

We lived there for five years.
He has been away since Tuesday.

We often use for and since when talking about time.

for + period: a “period” is a duration of time – five minutes, two weeks, six years. For means “from the beginning of the period to the end of the period”.

since + point: a “point” is a precise moment in time – 9 o’clock, 1st January, Monday. Since means “from a point in the past until now”.

Look at these examples:

for
a period
from start to end
since
a point
from then to now

>===<
x===>|

for 20 minutes
for three days
for 6 months
for 4 years
for 2 centuries
for a long time
for ever
since 9am
since Monday
since January
since 1997
since 1500
since I left school
since the beginning of time

all tenses
perfect tenses

for

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

• 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?

We do not use for with “all day”, “all the time”:

• I was there all day. (not for all day)

since

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.

We also use since in the structure “It is [period] since”:

• It was a year since I had seen her.
• How long is it since you got married?

• 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.

Both for and since also have other meanings, with no reference to time. Here are some examples: