Since vs For: Duration, Starting Point, and Tense

Quick Answer

Use for with a duration: for three hours, for a week. Use temporal since with a previous starting point: since noon, since 2022, since the alert fired.

The distinction is not a tense rule

Cambridge records for with periods in past, present, and future time. Since often accompanies a perfect tense because it locates the beginning of a span, but the surrounding timeline chooses the tense.

Classify the Time Phrase Before the Verb

Time job	Form	Question answered	Example
Measured duration	for	How long?	The review lasted for two hours.
Previous starting point	since	Starting when?	The issue has been open since Monday.
Start event	since + clause	Starting after what?	We have monitored it since the alert fired.
Named start and end	from ... to/until	From when to when?	She worked there from 2022 to 2025.

Cambridge’s for-or-since guide directly separates a period from a previous point. Its since/from/for comparison uses from, not since, when both endpoints are stated.

Four Repairs That Preserve the Timeline

Duration misread as a start:

I have worked here since five years.

Duration restored:

I have worked here for five years.

Five years measures the span. It does not locate the calendar point at which the work began.

Start misread as a duration:

The service has been offline for Tuesday.

Start restored:

The service has been offline since Tuesday.

Tuesday answers when the continuing state began. A duration version would need a measured span, such as for two days.

Closed range given a continuing marker:

She managed the account since 2022 to 2025.

Both endpoints exposed:

She managed the account from 2022 to 2025.

The sentence supplies a start and an end. From ... to represents that closed range directly.

Current state put in the simple present:

She works here since 2022.

Span reaches now:

She has worked here since 2022.

This intended timeline begins in 2022 and remains true now, so the present perfect makes that connection explicit.

For and Since Across Three Timelines

Reference point	Duration example	Starting-point example
Finished past	He worked there for two years.	Use a complete range if both dates matter: from 2022 to 2024.
Continuing to now	He has worked there for two years.	He has worked there since 2024.
Continuing to a past point	By June, he had worked there for two years.	By June, he had worked there since 2022.
Planned future duration	He will stay for two weeks.	Use from for a future start: He will stay from Monday.

The British Council’s how-long reference pairs for with duration and since with a starting point in present-perfect and past-perfect timelines. Its past-perfect reference gives both words in a timeline ending at a past reference point.

Since Can Mark Time or Give a Reason

Time

Since the database moved, latency has fallen.

The clause names the event that begins the measured period. It answers starting when?

Reason

Since the database is unavailable, postpone the migration.

Here since means approximately because. It answers why?, not starting when?

Cambridge’s since reference documents the preposition, conjunction, and adverb time uses, as well as the reason conjunction. The surrounding event meaning, not the word alone, disambiguates the two clauses.

Test the Timeline

1. The queue has been stalled ___ 9 a.m.

2. The pilot ran ___ eighteen months before it ended.

3. The archive covers 2018 ___ 2021.

4. By dawn, they had monitored the feed ___ midnight.

5. In “Since the office is closed, call tomorrow,” what does since express?

Live Check: One Detection, Two Different Repairs

On July 16, 2026, Grammarlyzer marked the exact phrase since five years. It offered for five years and since five years ago. The first preserves a duration; the second converts the phrase into a starting point. Choose according to the intended timeline.

Sentence to check:

Duration-preserving correction: I have worked at this company for five years.

Honest limits: The duration revision returned no issues. This test records one detected phrase and the engine’s two suggestions; it does not show how the checker handles every tense, since-clause, closed range, or reason use.

Frequently Asked Questions

What is the basic difference between since and for?

Use for with a duration, such as for three hours. Use temporal since with a previous starting point, such as since noon. A clause can also name that point: since the meeting ended.

Do since and for always require the present perfect?

No. For can describe duration in past, present, or future time. Since often appears with the present perfect for a state continuing to now and with the past perfect for a state continuing to a past reference point. The timeline, not either word alone, determines the tense.

Can a clause follow since?

Yes. A since-clause can name the event that starts the measured period, as in We have tracked the issue since the alert fired. Since can also introduce a reason, so check whether the clause answers starting when or why.

Can I write since 2022 to 2025?

Use from 2022 to 2025 when both the start and end are named. Temporal since looks back to a previous starting point; it is not the marker for a closed from-to range.

What did Grammarlyzer report for since five years?

On July 16, 2026, the checker flagged since five years and offered for five years and since five years ago. The first preserves a five-year duration; the second recasts the phrase as a starting point. The revision with for returned no issues.

What the Direct Sources Support

Cambridge: for or since? — periods across past, present, and future; previous starting points; and the warning against since + period.
Cambridge: since, from, or for? — from for named start/end ranges and for for general periods.
Cambridge: since — time preposition, conjunction, adverb, tense patterns, and reason conjunction.
British Council: how long — duration with for, starting points with since, and bounded ranges with from ... to/until.
British Council: past perfect — for and since in spans measured to a past reference point.

These sources do not support the removed claims that this pair belongs only to the present perfect, that a particular cross-language transfer explains the error for all learners, or that the checker can resolve every intended timeline.

A Four-Step Since-or-For Audit

Draw the span. Mark its beginning, endpoint, and whether the endpoint is now, a past reference point, or a future plan.
Classify the phrase. A measured span takes for; a previous start takes temporal since; two named endpoints take from ... to/until.
Read any since-clause. Decide whether it names a start event or supplies a reason.
Choose the tense separately. Make the verb match the complete timeline instead of treating either preposition as an automatic tense command.

What This Page Adds to the Time Cluster

The time and progression hub routes among sequence, comparison, completed movement, and tense markers. This page performs the narrower duration-versus-starting-point audit and tests the boundary with closed ranges and reason clauses.

Present perfect vs simple past chooses a verb timeline; it does not fully compare for, since, and from ... to. In, on, and at chooses the preposition inside a clock or calendar expression; this page decides how that expression relates to a measured span.

The inventory-listed will vs going to page chooses between future forms. Its direct link relationship does not duplicate this page’s time-span decision.

Check the Phrase, Then Map the Timeline

Use the checker for a first pass. When it offers more than one grammatical repair, use the four-step audit to preserve the meaning you intended.

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