Since vs For: Difference, Rules & Examples

Since and for both help us talk about time, but they answer different questions. Use since to identify when a period began and for to describe how long it lasts.

Imagine a team started working at 9 a.m. and is still working at noon.

The team has been working since 9 a.m.

The team has been working for three hours.

The first sentence identifies the starting time. The second tells us how long the team has been working.

The choice of preposition is important, but the verb tense also helps us understand whether a situation is continuing or finished.

Since vs For: Quick Comparison

Since commonly appears with perfect tenses when a period extends from an earlier point to the present or another reference time.

For can describe durations in the past, present, or future. It is not restricted to perfect tenses.

When to Use Since

Use since when you want to identify the beginning of a period.

The museum has been closed since Tuesday.

I haven’t spoken to Daniel since our last meeting.

Tuesday and the last meeting provide the starting points.

The starting point does not need to be an exact date or clock time.

They’ve known each other since childhood.

The building has been empty since the previous owner moved away.

Here, childhood identifies an earlier period, while the owner’s departure identifies an event.

Since with Dates, Time Expressions, and Clauses

When since is followed by a date or noun phrase, it functions as a preposition in traditional grammar.

I’ve worked remotely since January.

She’s been interested in photography since childhood.

Since can also introduce a clause containing a subject and verb.

We’ve kept in touch since we left university.

I’ve worked remotely since I changed jobs.

In traditional grammar, since functions as a conjunction in these examples because it introduces a clause.

The meaning is still related to a starting point, but the grammatical structure is different.

When to Use For

Use for to describe the length of a period.

The exhibition stayed open for six weeks.

We’ve been discussing the proposal for nearly an hour.

The first sentence describes a completed period. The second describes a discussion that began earlier and has continued up to the present or very recently.

A duration does not have to be exact.

I haven’t visited that town for ages.

The technician was away for a while.

Expressions such as a while, several months, two hours, and a long time describe lengths of time.

Why We Say For Three Years, Not Since Three Years

In the ordinary duration construction, use for.

Incorrect: She has worked here since three years.

Correct: She has worked here for three years.

To use since, identify when the employment began.

She has worked here since she graduated.

Or give a year or another starting point:

She has worked here since 2023.

The choice depends on whether you’re naming a starting point or a duration.

How Verb Tense Changes the Meaning

Two sentences can use the same time expression but describe different situations because their verb tenses differ.

Present Perfect: A Period Continuing to the Present

The present perfect commonly describes situations that began in the past and remain true.

The family has owned the cottage since 2016.

The family has owned the cottage for many years.

The family still owns the cottage in the ordinary reading of these sentences.

The present perfect continuous often emphasizes an activity taking place over a period.

The engineers have been testing the equipment since Monday.

The engineers have been testing the equipment for four days.

Both sentences describe activity continuing up to the present or very recently.

However, some verbs describing states are not normally used in continuous forms with these meanings.

Incorrect: I’ve been knowing Sara for ten years.

Correct: I’ve known Sara for ten years.

The present perfect simple is the natural choice with know in this meaning.

Past Simple: A Completed Period

Compare:

Elena lived in Dublin for four years.

Elena has lived in Dublin for four years.

The first presents the four years as a completed period in the past. It commonly suggests that Elena no longer lives there.

The second normally indicates that Elena moved to Dublin four years ago and still lives there.

The duration is unchanged. The tense tells us how the period relates to the present.

Future Time: How Long Something Will Last

For can also describe a future duration.

The gallery will close for two weeks during the renovation.

We’re planning to stay in Edinburgh for five days.

Neither sentence requires a perfect tense.

Past Perfect: Looking Back from a Past Moment

With the past perfect, since and for can describe a period leading up to a reference point in the past.

When the technician arrived on Thursday, the lift had been out of service since Monday.

By the time the technician arrived, the lift had been out of service for three days.

The period is measured up to the technician’s arrival rather than up to the present.

Does Since Always Describe an Uninterrupted Action?

No. This is an important distinction.

Consider:

The library has been closed since Friday.

The closure began on Friday and continues to the present.

Now compare:

The library has received three deliveries since Friday.

The deliveries may have happened at separate times. They are completed events within a period that began on Friday.

Since identifies the beginning of the period, but it does not mean every event within that period was continuous.

The maintenance team has repaired five machines since Monday.

This tells us how many repairs were completed during that period. It does not mean the team worked continuously without a break.

It’s Been Three Years Since: A Different Construction

A duration can appear before since in expressions such as It’s been three years since…

Consider:

I’ve lived in Bristol for three years.

This normally means I moved to Bristol three years ago and still live there.

Now compare:

It’s been three years since I last visited Bristol.

This means my last visit was three years ago. It does not mean I’ve been visiting Bristol continuously for three years.

The construction works like this:

It’s been + duration + since + event

Examples:

It’s been six months since we last spoke.

It’s been two years since the museum reopened.

In these sentences, since introduces an earlier event, while the duration measures the time elapsed since that event.

You may also encounter It’s two years since…, particularly in British English. Both patterns are established.

Since Then, Ever Since, and Since Meaning Because

Since has several grammatical uses beyond appearing directly before a starting date.

Since Then and Ever Since

When the starting point is understood, we can use since or since then as an adverbial expression.

They moved into their new office in April and have expanded the team since then.

Since then refers back to the office move.

Ever since places additional emphasis on the period beginning at an earlier event.

I visited the village as a child and have wanted to return ever since.

The earlier visit provides the starting point.

Since Can Also Mean Because

Not every since refers to time.

Since the roads are flooded, the delivery will be postponed.

Here, since introduces a reason and has a meaning similar to because.

Compare:

The delivery has been delayed since Monday.

This sentence identifies when the delay began.

Since vs From, and For vs In

Other time expressions can sometimes cause confusion because they describe related periods.

Since vs From

Since commonly introduces an earlier point from which a period extends to the present or another reference time.

Maya has worked at the museum since 2019.

When both the beginning and end of a completed period are specified, from … to is usually more appropriate.

Maya worked at the museum from 2019 to 2023.

Incorrect: Maya worked at the museum since 2019 to 2023.

Correct: Maya worked at the museum from 2019 to 2023.

The second sentence gives both boundaries of a completed period.

For vs In: Duration or Time Until an Event?

Compare:

The manager will work in London for six months.

The manager will move to London in six months.

For six months tells us how long the work will last.

In six months tells us how much time will pass before the move happens.

Another useful contrast is:

She worked on the report for two hours.

She finished the report in two hours.

The first describes time spent working. The second tells us how long completion took.

When For and In Can Both Be Correct

There is also an important overlap in negative sentences.

I haven’t heard from her for five years.

I haven’t heard from her in five years.

Both can mean that five years have passed without any contact. The use of in in this construction is particularly common in American English, although it is not exclusive to American usage.

The choice between for and in depends on the construction, rather than one fixed rule applying to every sentence.

How Since, For, and Verb Tense Work Together

Imagine a repair team fixing a faulty heating system. Looking at the same job at different times shows how English describes its beginning, duration, and completion.

Monday, 9 a.m.: The Repair Begins

The engineers start working on the heating system.

Monday, Noon: Work Is Still Underway

The team has been repairing the system since 9 a.m.

The team has been repairing the system for three hours.

Monday, 1 p.m.: The Repair Is Completed

The engineers finish the job.

The team worked on the system for four hours.

The past simple presents the job as completed.

Friday, 1 p.m.: Looking Back

Four days have passed since the repair was completed, and there have been no further problems.

There haven’t been any heating problems since the repair was completed.

It’s been four days since the repair was completed.

The first reports the absence of problems during the period. The second measures the time elapsed since completion.

Each sentence describes the repair from a different point in time.

Check Your Understanding

These questions test starting points, durations, verb tense, and meaning. Some require more than selecting a familiar time expression.

1. Starting Point or Duration?

A train service began operating at 6 a.m. It is now 9 a.m., and the service is still running.

Which descriptions are correct?

A. The service has been running since 6 a.m.

B. The service has been running for three hours.

C. Both A and B.

2. Completed or Continuing?

A journalist worked in London for eight years before moving to Edinburgh.

Which sentence normally describes that completed period?

A. The journalist worked in London for eight years.

B. The journalist has worked in London for eight years.

3. Separate Completed Events

A technician has repaired five machines since Monday.

Does this mean the technician has been working continuously since Monday?

A. Yes. Since always indicates one uninterrupted action.

B. No. The repairs may have happened at separate times.

4. It’s Been Three Years Since…

Someone last visited Paris three years ago.

Which sentence describes that situation?

A. I’ve lived in Paris for three years.

B. It’s been three years since I last visited Paris.

5. For or In?

Someone started writing a report at 10 a.m. and finished it at noon.

Which sentence explicitly describes the time needed to complete the report?

A. She worked on the report for two hours.

B. She finished the report in two hours.

6. Negative Sentences

A person last spoke to an old friend five years ago.

Which sentences can correctly express that period without contact?

A. I haven’t spoken to my friend for five years.

B. I haven’t spoken to my friend in five years.

C. Both A and B.

Answers and Explanations

1. C. Both are correct. Since 6 a.m. identifies the starting time, while for three hours describes how long the service has been running.

2. A. The past simple presents the eight-year period as completed. The present perfect would normally suggest the employment has continued up to the present.

3. B. Since Monday identifies the beginning of the period in which five repairs were completed. It does not establish uninterrupted work.

4. B. It’s been three years since I last visited Paris measures the time since the last visit. Sentence A describes a period of residence, not an earlier visit.

5. B. Finished the report in two hours explicitly states the time needed for completion. Sentence A describes how long she worked on the report, which does not by itself establish whether she finished it.

6. C. Both sentences are correct. In negative constructions of this kind, for five years and in five years can communicate the same elapsed period without contact.

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