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Confused About Using 'Since' vs 'For' in Talking About Time in My Emails

Asked byJin ParkPosted Mar 27, 2026 2:10 AM3 answers24 upvotesCanonical URL

I'm writing an email to a colleague to explain how long I've been working on a project, but I'm not sure if I should say, "I've worked on this since two weeks" or "I've worked on this for two weeks." I often get mixed up about when to use 'since' and when to use 'for.'

This always comes up when I talk about how long I've lived somewhere or done something. For example, should I say, "I've lived here since five years" or "I've lived here for five years"? Could someone explain how to choose between these two words? Some tips or simple rules would be really helpful!

Context:
Business writing, non-native English speaker, formal tone

#word-choice#esl#formal-vs-informal

What to Know

Question You Likely Still HaveDirect AnswerHow To Apply It
What is the core rule for confused using since talking?(Starting point) Self-Check Practice: Try rewriting your sentence with both words: "I've worked on this ___ two weeks." If your answer is about the period ('two weeks'), use 'for'…Explanation: When you talk about the duration of an activity, the choice between 'since' and 'for' depends on whether you mean the starting point or the length of time.
How do I apply confused using since talking in a sentence like mine?Explanation: When you talk about the duration of an activity, the choice between 'since' and 'for' depends on whether you mean the starting point or the length of time.Use 'since' + the exact starting point: 'since' tells us when something began (a specific moment/point in time).
What mistakes should I avoid with confused using since talking?Use 'since' + the exact starting point: 'since' tells us when something began (a specific moment/point in time).Use 'for' + the length/duration: 'for' tells us how long something has been happening (a period of time).

3 Answers

ByNora GrammarMar 27, 2026 2:30 AM9 upvotesAccepted answer

Explanation:
When you talk about the duration of an activity, the choice between 'since' and 'for' depends on whether you mean the starting point or the length of time.

  • Use 'since' + the exact starting point:
    • 'since' tells us when something began (a specific moment/point in time).
  • Use 'for' + the length/duration:
    • 'for' tells us how long something has been happening (a period of time).

Examples:

  • I've been with the company for three years. (Length/duration)
  • I've been with the company since 2021. (Starting point)

Self-Check Practice:
Try rewriting your sentence with both words:

  • "I've worked on this ___ two weeks."
    If your answer is about the period ('two weeks'), use 'for': ✔️ "for two weeks"
    If your answer specifies a starting date, use 'since': e.g., "since June 1st"

Correction:

  • ❌ I've lived here since five years.
  • ✔️ I've lived here for five years.
  • ✔️ I've lived here since 2019.

This pattern can be used in all time-related sentences.

ByRavi AdminMar 27, 2026 3:10 AM8 upvotes

Rule by Questions:
When choosing 'since' or 'for', ask yourself: Am I explaining from when something started, or how long it has continued?

  • If your answer is a point in time (when): Use 'since'.
  • If your answer is a length of time (how long): Use 'for'.

Example Guidance:

  • "Have you known her ___ 2020?" (when? -- Use 'since')
  • "Have you known her ___ three years?" (how long? -- Use 'for')

Try This:
Write a couple of sentences about your work history, using both patterns:

  • "I've managed this account ___ last April."
  • "I've managed this account ___ one year."
    Check: Is the blank filled by a date/event (since) or a duration (for)?

Self-Editing Tip:
If you ever use 'since' with a period (like 'since five years'), swap for 'for'. With a date like 'since June 2022', keep 'since'.

ByPunctuation PaulMar 27, 2026 2:50 AM7 upvotes

Clear Contrast:
Think of 'since' as tying you to a calendar date or event, while 'for' tells someone the total amount of time.

  • 'Since' => when you started (date, day, event)
  • 'For' => total duration (hours, days, years)

Business Email Examples:

  1. FOR: "I have supervised this process for six months."
  2. SINCE: "I have supervised this process since January."

Practice Tip:
Take a sentence and make two versions, switching the time expression:

  • "We have worked together ___ last summer."
  • "We have worked together ___ six months."
    Decide: use 'since' with dates (last summer), 'for' with durations (six months).

Correction advice:
If you see a number + time unit (days, weeks, years) without a specific date/event, you usually want 'for'.
If you see a calendar date, year, or named event, use 'since'.

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