WHICH WORD?

for or since

UPDATED:  NOV 2021

for


= duration or period of time 
​
= 5 days, 2 weeks, many months, several years, most of my life, a long time.)

= usually used with a number (for 10 days, for 2 years)

NOTE:
You can use with All tenses.

NOTE:
Usually answers the question “How long”.

​EXAMPLES:

  • How long were your at the University of Sydney in Australia?
    For five years.
    ​
  • How long have you worked in Dallas? 
    For 2 years.

  • Fahad has been living in Brisbane for over 3 years.

since


= a specific time in the past (last week, last month, last year, March, 1999)

NOTE: 
​You can’t use with simple present tense. 

“I work with her for a long time.” <= incorrect

NOTE:  
You must use Present Prefect or Prefect Continuous


EXAMPLES:
​
  • How long have you been here at the UC Berkeley?   
    Since July of 2019.

  • ​Mary has worked in New York since just after 9/11. 

  • Bob has studied Arabic for a year.