When to Use since or for in English

Choosing between since and for depends on what you want to say about time. Use since to point to a specific starting point (a moment or event), and use for to talk about a duration (a length of time). This is the core rule that will help you avoid the most common mistakes in everyday writing, emails, and conversation.

Quick Answer

Since = from a specific point in time (e.g., since Monday, since 2020, since I arrived).
For = a period of time (e.g., for two hours, for a week, for a long time).

If you can answer “when did it start?” use since. If you can answer “how long?” use for.

Understanding the Difference

Since: The Starting Point

Since tells us when an action or situation began. It always refers to a specific moment, date, or event. It is most commonly used with the present perfect or past perfect tense, though you will also hear it in informal conversation with the simple past.

Examples:

• I have worked here since 2018.
• She has been feeling better since Tuesday.
• They have not spoken since the argument.

For: The Duration

For measures the length of time an action lasts. It works with any tense and is used to describe how long something continues.

Examples:

• I have worked here for six years.
• She has been feeling better for three days.
• They waited for an hour.

Comparison Table

Natural Examples

Here are examples from real situations, including conversation and email contexts.

• Conversation: “I haven’t seen you since the party last month.”
• Email: “I have been out of the office since Friday.”
• Conversation: “We talked on the phone for an hour last night.”
• Email: “The project has been delayed for two weeks.”
• Formal writing: “The company has reported losses since the third quarter.”
• Informal note: “I have been waiting for ages!”

Common Mistakes

Even advanced learners sometimes mix these up. Here are the most frequent errors.

• Mistake: “I have been here since three hours.”
  Correction: “I have been here for three hours.” (Three hours is a duration, not a starting point.)
• Mistake: “She has worked here for 2020.”
  Correction: “She has worked here since 2020.” (2020 is a specific year, a starting point.)
• Mistake: “I haven’t eaten for breakfast.”
  Correction: “I haven’t eaten since breakfast.” (Breakfast is a specific event, a starting point.)
• Mistake: “They are on holiday since a week.”
  Correction: “They are on holiday for a week.” (A week is a duration.)

Better Alternatives and When to Use Them

In some situations, you can rephrase your sentence to avoid confusion. This is especially helpful in formal writing or emails.

• Instead of “I have known her since 2010,” you can say “I have known her for 14 years.” Both are correct, but the second emphasizes the length of the relationship.
• Instead of “I have been waiting for 30 minutes,” you can say “I have been waiting since 2:30.” The first focuses on the duration, the second on the start time.
• In email subject lines, use for to state a deadline: “Out of office for two days.” Use since to explain a change: “Updated policy since January.”

Mini Practice

Test your understanding. Choose since or for for each sentence. Answers are below.

1. I have been studying English _____ 2019.
2. We have lived in this city _____ five years.
3. She hasn’t called me _____ last weekend.
4. They have been working on the report _____ three days.

Answers:

1. since (2019 is a specific year)
2. for (five years is a duration)
3. since (last weekend is a specific point)
4. for (three days is a duration)

FAQ

1. Can I use “since” with the simple past tense?

Yes, in informal conversation. For example, “I saw him since Monday” is common in spoken English, but in writing, it is better to use the present perfect: “I have seen him since Monday.”

2. What is the difference between “since” and “from”?

“Since” is used with a starting point that continues to the present. “From” is used to describe a starting point without implying continuation. For example, “I work from 9 to 5” does not mean I am still working now. “I have worked since 9” means I started at 9 and am still working.

3. Can “for” be used with a specific point in time?

No. “For” always requires a duration. You cannot say “for 2020.” You must say “since 2020” or “for the year 2020” (which treats the year as a duration).

4. Is there a trick to remember the difference?

Think of “since” as pointing to a start date on a calendar, and “for” as measuring a length on a ruler. If you can put a date or event after the word, use “since.” If you can put a number of hours, days, or years, use “for.”

For more help with similar word choices, explore our Usage Confusions guides. If you have questions about this article, please contact us. To understand how we create accurate content, see our Editorial Policy.