Simple explanation
Why do we use for and since with the present perfect? The present perfect can connect a past starting point with the present. We often use it for situations that began in the past and are still true now. For and since add information about time. In I have lived here for five years, the five-year period continues up to now. In I have lived here since 2021, 2021 tells us when the situation started. The main difference between for and since The easiest way to choose between for and since is to think about two questions: How long? and Since when? Use for when you give a duration: for two hours, for six months, for many years. Use since when you give the starting point: since Monday, since 2020, since last summer. The important difference is meaning, not simply the type of word that follows. Using for to express duration For introduces a period of time. The period can be exact, such as for three weeks or for ten years, or less exact, such as for a while or for a long time. In We have known each other for eight years, for eight years tells us the length of the relationship up to the present. Using since to express a starting point Since introduces the point in the past when a situation began. The starting point can be a year, day, time, period, or event: since 2019, since Tuesday, since 8 o'clock, since last summer. In She has worked here since 2022, the year 2022 marks the beginning of her employment. Using since before a clause Since can also be followed by a clause describing the event that marked the beginning of a situation. For example, I have known Maya since we started university. The clause we started university identifies when the relationship began. When this clause refers to a completed starting event, it commonly uses the past simple. Affirmative and negative forms The basic affirmative structure is subject + have/has + past participle. Use has with he, she, and it, and have with I, you, we, and they. To make the sentence negative, use haven't or hasn't before the past participle. The choice between for and since remains the same: for expresses duration, while since identifies the starting point. Questions with How long How long is commonly used to ask about the duration of a situation that continues into the present. The usual structure is How long + have/has + subject + past participle? For example, How long have you worked here? You can answer with a duration, such as For four years, or with a starting point, such as Since 2022. For and since do not automatically require the present perfect For and since are not exclusive to the present perfect and can appear in other structures. Do not choose a tense simply because you see one of these words. In this lesson, the focus is their common use with situations that started in the past and remain connected to the present. Always consider the meaning of the whole sentence.
Grammar formula
Affirmative with for
Subject + have/has + past participle + for + period of timeI have worked here for three years.
Affirmative with since
Subject + have/has + past participle + since + starting pointShe has lived here since 2022.
Negative form
Subject + haven't/hasn't + past participle + for/since + time expressionWe haven't seen him since Friday.
Yes/no question
Have/Has + subject + past participle + for/since + time expression?Have you known Anna for a long time?
How long question
How long + have/has + subject + past participle ...?How long have you lived in this city?
Core rules
- 1
Use for with a duration
Use for + period of time to say how long a situation has continued: for two days, for six months, for several years, for a long time.
- 2
Use since with a starting point
Use since + starting point to say when a continuing situation began: since Monday, since 2020, since last summer.
- 3
Since can introduce a clause
Use since before a clause when an event marks the beginning of the situation: since I moved here, since we met, since she started university.
- 4
Choose have or has according to the subject
Use have with I, you, we, and they. Use has with he, she, and it. The main verb then appears as a past participle.
- 5
Use the past participle after have or has
The present perfect requires have/has + past participle: live → lived, work → worked, know → known, see → seen, be → been.
- 6
Use How long to ask about duration
Use How long + present perfect to ask how long a continuing situation has existed. The answer can use for to give the duration or since to give its starting point.
Useful examples
I have lived in this neighborhood for five years.
I started living in this neighborhood five years ago, and I still live here.
For five years expresses the duration of the continuing situation.
Emma has worked at the hospital since 2021.
Emma started working at the hospital in 2021 and still works there.
Since 2021 identifies the starting point.
We have known each other for a long time.
We met a long time ago, and we still know each other now.
For a long time gives an approximate duration rather than an exact one.
My parents have owned this house since I was a child.
My parents got this house when I was a child, and they still own it.
Since is followed by a clause that identifies the beginning of the situation.
I haven't seen Leo for two weeks.
The last time I saw Leo was two weeks ago.
For two weeks describes the length of time without seeing Leo.
She hasn't called me since Monday.
Her last call was on or before Monday, and she has not called after that point.
Since Monday marks the beginning of the period without a call.
Have you had this phone for long?
Have you owned this phone for a long period of time?
For long is natural in questions about duration.
How long have you known your best friend?
When did your friendship begin, and how much time has passed since then?
How long asks about the duration of a relationship that still exists.
They have been married since 2018.
They got married in 2018, and they are still married now.
Since 2018 gives the starting year of the marriage.
I've had this laptop for nearly four years.
I got this laptop almost four years ago, and I still have it.
Nearly four years is a period of time, so for is required.
Daniel has played in this team since he moved to London.
Daniel started playing in the team when he moved to London and still plays in it.
The clause after since describes the event that marked the beginning.
We haven't eaten at that restaurant since we moved to this area.
Our move to this area is the point after which we have not eaten at that restaurant.
Since connects a past starting event with the period continuing to the present.
Common mistakes
- ❌ I have lived here since five years. ✅ I have lived here for five years. Five years is a duration, not a starting point, so for is required.
- ❌ She has worked here for 2022. ✅ She has worked here since 2022. 2022 identifies when the situation started, so use since.
- ❌ I live here since 2020. ✅ I have lived here since 2020. When the meaning is that the situation started in 2020 and continues now, standard English normally uses the present perfect.
- ❌ He have known her for ten years. ✅ He has known her for ten years. The subject he requires has, not have.
- ❌ We have knew each other since school. ✅ We have known each other since school. After have, use the past participle. Known is the past participle of know; knew is the past simple form.
- ❌ How long do you know Sarah? ✅ How long have you known Sarah? The question refers to a relationship that began in the past and continues now, so the present perfect is appropriate.
- ❌ I haven't seen him since three months. ✅ I haven't seen him for three months. Three months describes a period of time, so use for rather than since.
Learning tips
- Ask yourself one simple question: Is this a duration or a starting point? Duration → for. Starting point → since.
- Common expressions with for include for two hours, for three weeks, for several years, and for a long time.
- Common expressions with since include since Monday, since 2020, since last week, and since I moved here.
- Do not translate words mechanically from your first language. Focus on whether the English time expression represents a period or a starting point.
- A How long question does not need to contain for or since. The answer can provide either the duration with for or the starting point with since.
- Pay attention to irregular past participles: know → known, see → seen, be → been, have → had.
- Do not choose the present perfect only because a sentence contains for or since. First check whether the situation has a meaningful connection with the present.
Practise this topic
Interactive exercises for this topic are coming soon.
PlannedRelated grammar
Related dictionary words
Frequently asked questions
How can I quickly decide between for and since?
Ask whether the time expression gives a duration or a starting point. Use for with a duration, such as for three months, and since with a starting point, such as since March.
Can a complete clause come after since?
Yes. Since can introduce an event that marks the beginning of the situation, as in I have lived here since I started university.
Which tense is normally used after since in “since I moved here”?
When the clause describes a completed event that marks the starting point, the past simple is common: since I moved here, since we met, or since she started university.
Why is “How long do you know him?” usually incorrect?
Know describes a state that began in the past and continues in the present. In this meaning, standard English normally uses the present perfect: How long have you known him?
Can I answer a How long question with since?
Yes. How long have you worked here? can be answered with a duration, such as For five years, or a starting point, such as Since 2021.
Are for and since only used with the present perfect?
No. Both words have other uses and can occur with other grammatical structures. Their use with the present perfect is especially important when describing a past-to-present situation.