How are ‘since’ and ‘for’ used? (Explanation)

The English time adverbs ‘for’ and ‘since’ are often confused, as they principally mean the same thing – but cannot be used exactly in the same way. There is an important distinction: If the statement includes a period of time or a time span (for example, ‘for three weeks’), ‘for’ needs to be used, whereas a point in time (for example, ‘since seven o’clock’) requires the use of ‘since’. Compare the following cases in detail:

1. Make use of ‘for’ if time periods are expressed:
   • First, for better understanding of time spans or periods (in this case from past to present) take a look at the graphical representation (timeline):
     • 
   • Examples of using ‘for’ in sentences:
     • “I have known him for three years.”
       • time span
     • “She has been waiting for a long time.”
       • time span
     • “We have been standing here for 30 minutes.”
       • time span
2. However, ‘since’ is utilized if points in time are mentioned:
   • Consider the illustration for clarification what a point in time in the past means:
     • 
   • Examples of using ‘since’ in sentences:
     • “I have been working here since 5 o’clock.”
       • point in time
     • “She has been very generous since the day she won the lottery.”
       
       • point in time
     • “Since 2001, they have changed the security guidelines very often.”
       
       • point in time
3. Attention: Be careful not to confuse ‘since’ for a point in time with ‘ago’ which is also used for points in the past. However, ‘ago’ does not describe a time span starting in the past and reaching up to now. Compare:
   • “I bought my car three years ago.”
     • The sentence means that the person got the car back then, but not necessarily that he still has it.
   • “Sabrina moved to Paris a long time ago.”
     • She moved to Paris at a date in the past, but it is unknown if she still lives there.

Special cases when using ‘since’ and ‘for’

When learning the language it is helpful to know that the adverbs ‘since’ and ‘for’ often appear in combination with the following tenses:

1. Usage of ‘since’ and ‘for’ with the present perfect simple:
   • “I’ve lived in this town for 15 years now.”
2. … and the present perfect continuous:
   • “Sue has been studying English since May.”
3. Also, ‘for’ and ‘since’ frequently occur with the past perfect simple:
   • “Before Peter came to Germany, he had lived in Australia for 10 years.”
4. … and the past perfect continuous:
   • “Before we bought the present, we had been thinking about it for quite a while.”

‘since’ or ‘for’ – dropdown (difficulty: 3 of 5 – medium)

For the gaps, choose either ‘since’ or ‘for’, which are frequently used with the present perfect. Consequently, you have to differentiate between a point in time and a period.

• Example: “Jill has been sleeping since two o’clock.”

If you still need help with the topic, have a look at the use of ‘since & for’ again.

Further exercises and explanations referring to the ‘Use of ‘since’ and ‘for’’

The following exercises and explanations are related to the topic ‘Difference and usage of ‘since’ and ‘for’ in English’:

• Prepositions of time in the English language
• The difference of time span and point in time in detail
• Using the present perfect simple
• Using the present perfect continuous
• Exercise 2: ‘since’ and ‘for’