Small words like “for” and “since” cause big confusion because both talk about time—but they answer different questions.
- “I’ve lived here for 5 years.”
- “I’ve lived here since 2020.”
At first glance, they look similar. In reality, they’re not interchangeable—and using the wrong one instantly sounds off.
Quick Answer
- “For” = duration (how long)
- “Since” = starting point (from when)
✔ I’ve studied for 2 hours.
✔ I’ve studied since 9 AM.
That’s the core rule—but there’s more nuance below.
Why People Confuse Them
The confusion comes from three main reasons:
- Both are used with perfect tenses (“I have lived…”)
- Both relate to time
- Both can appear in very similar sentence structures
❌ I’ve lived here since 5 years (wrong)
✔ I’ve lived here for 5 years
Same structure, different logic—that’s the trap.
Key Differences At A Glance
| Feature | For | Since |
|---|---|---|
| Meaning | Duration | Starting point |
| Answers | “How long?” | “From when?” |
| Example | for 3 days | since Monday |
| Time Type | Period | Specific point |
| Flexibility | Very broad | More specific |
Meaning and Usage Difference
1. “For” = Duration (Length of Time)
Use “for” when talking about a period or length of time.
✔ for 10 minutes
✔ for a week
✔ for many years
Examples:
- I waited for two hours.
- She has worked here for a long time.
Think: stretch of time
2. “Since” = Starting Point
Use “since” when you mention when something started.
✔ since 2020
✔ since Monday
✔ since morning
Examples:
- I’ve lived here since 2020.
- He has been sick since yesterday.
Think: starting moment → now
3. Timeline Visualization
- For → covers a duration
→ ▬▬▬▬▬ (length) - Since → starts at a point
→ ●▬▬▬▬ (start → now)
4. “Since” Also Means “Because”
This is where many learners get confused.
✔ Since you’re here, let’s start. (= because)
This meaning is completely different from time usage.
Tone, Context, and Formality
- Both are neutral and common in everyday English
- “For” is more flexible (used beyond time too)
- “Since” can sound slightly more formal when used as “because”
✔ I’ve worked here for years (natural)
✔ I’ve worked here since 2021 (natural)
No major tone difference—just different functions.
Which One Should You Use?
Ask yourself one simple question:
👉 Am I talking about duration or a starting point?
- Duration → use for
- Starting point → use since
Step-by-step examples:
- “5 years” → duration → ✔ for 5 years
- “2019” → starting point → ✔ since 2019
When One Choice Sounds Wrong
Some combinations just don’t work:
❌ since 5 years
✔ for 5 years
❌ for Monday (when meaning start time)
✔ since Monday
Why?
- “Since” needs a specific starting point
- “For” needs a time length
Common Mistakes
Mistake 1
❌ I’ve known him since 10 years
✔ I’ve known him for 10 years
👉 Fix: Use “for” with durations
Mistake 2
❌ I’ve been here for Monday
✔ I’ve been here since Monday
👉 Fix: Use “since” with dates/days
Mistake 3
❌ I live here since 2020
✔ I have lived here since 2020
👉 Fix: “Since” often requires perfect tense
Mastering time expressions like for and since becomes easier when you understand verb agreement. Learn more in our guide on has vs have in English grammar.
Everyday Examples
Daily Conversation
- I’ve waited for hours.
- I’ve been awake since 6 AM.
Work
- She has worked here for 3 years.
- She has worked here since 2023.
School
- I’ve studied English for a long time.
- I’ve studied English since childhood.
Dictionary-Style Word Details
Part of Speech
- For → Preposition
- Since → Preposition + Conjunction
Synonyms (Context-Based)
- For → during, over (partial)
- Since (time) → from
- Since (cause) → because
Example Sentences
- I’ve waited for a while.
- I’ve been here since morning.
- Since you asked, I’ll explain.
Word History
- For → Old English, broad usage over time
- Since → Old English, developed dual meaning (time + cause)
Common Phrases
- For: for years, for a while, for good
- Since: since then, ever since, since when
FAQ
What is the main difference between for and since?
“For” shows a duration of time, while “since” shows a starting point in time.
Examples:
- I’ve worked here for 5 years.
- I’ve worked here since 2021.
Do we use “for” with periods of time?
Yes. Use “for” with lengths or durations of time.
Examples:
- for two hours
- for a week
- for many years
Do we use “since” with specific times and dates?
Yes. Use “since” with a specific starting point.
Examples:
- since Monday
- since 2020
- since breakfast
Which is correct: “since 5 years” or “for 5 years”?
✅ for 5 years
❌ since 5 years
“5 years” is a duration, so “for” is correct.
Can “since” also mean “because”?
Yes. “Since” can also introduce a reason.
Example:
- Since you’re here, let’s begin.
Here, “since” means “because,” not time.
Why is “I live here since 2020” incorrect?
Because “since” usually works with perfect tenses.
✅ I have lived here since 2020.
❌ I live here since 2020.
Is “for” only used for time?
No. “For” has many meanings besides time.
Examples:
- This gift is for you.
- We left for London.
- I waited for an hour.
Can “for” and “since” ever be interchangeable?
No. They describe different ideas:
- “for” = duration
- “since” = starting point
So they cannot replace each other directly.
What is the easiest way to remember for vs since?
Use this quick memory trick:
- For → how long
- Since → from when
Examples:
- for three months
- since January
Are for and since important in English exams?
Yes. This is a very common grammar topic in school tests, ESL exams, and English writing assessments because it checks understanding of time expressions and verb tense structure.
Conclusion
The difference is simple—but powerful:
- “For” = duration (how long)
- “Since” = starting point (from when)
✔ I’ve lived here for 5 years
✔ I’ve lived here since 2020
Master this distinction, and your English instantly sounds more natural and precise.
