I am often confused with the usage of since and from.

I know him from 15 years

I know him since 15 years.

Which one is correct? How would I decide which is the right preposition to use?


'Since' and 'From'

'Since' talks about one particular point of time till now.

I have been working since 7 am

'From' in most of the cases talks about the starting point and ending point. Said that, the format could be 'from....to/till/until'

The shop is open from 9 in the morning to 6 in the evening

Quite close is 'since' and 'for'

'Since' and 'For'

Okay, as I said, 'since' talks about a particular point. So, you need to mention "since" which date the thing has been happening.

On the other hand, 'for' is used for a total period of time and you don't need to define a starting point.

The best example I can think of is...

I have been waiting for two hours


I have been waiting since 2 o'clock

In the latter example, you need to define the starting point.

Another example:

I have been living in this house for 10 years
I have been living in this house since 2005

So, in your case, you have known him for the past 15 years OR since 2000.

  • 1
    Not direct to the question; but in the last sentence, you need a past tense to describe the past: "You have known him for the past 15 years," or "You have known him since the year 2000." – Evelyn Mar 18 '15 at 6:08
  • 1
    @Evelyn Or, if your knowledge of him is an episode from the past and not continuous, you could say I know him from 15 years ago. – choster Mar 18 '15 at 7:05
  • @choster, you're quite right. That usage is almost always followed by specifics of the episode: "I know him from 15 years ago, when we spent a summer working as deckhands on the same fishing trawler." – Evelyn Mar 18 '15 at 7:31
  • 1
    still needs 'for the past 15 years' in your last para, or 'for 15 years'. 'past' has to take 'the' – gone fishin' again. Mar 18 '15 at 9:53
  • @Tetsujin, buddy, you could have done it. :) – Maulik V Mar 18 '15 at 9:58

When we use 'since' we generally refer to a particular point of time or a specified time in the past. For example - He has been living here since 1988. She has been awake since dawn / 5'o clock. They have been working here since their youth. So the sentence - " I know him since 15 years " - is wrong. The correct form is - " I know him for 15 years ".

In the same way ' from ' is also used to refer to a particular point of time, and in addition to it, it can also be used to refer to the starting point as well as the ending point. For example - The world cup will start from 14th February. We lived in Oslo from 1988 to 2009.

To refer to a period of time we generally use 'for'. For example - It has been raining in New York for three days.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.