say for certain

USAGE SUMMARY

"say for certain" is correct and usable in written English. You can use it when expressing a degree of certainty or assurance about something. Example: "I can't say for certain if the meeting will happen tomorrow." Alternative expressions include "be sure" and "confirm."

✓ Grammatically correct

Academia

Formal & Business

News & Media

Science

Encyclopedias

Human-verified examples from authoritative sources

Exact Expressions

60 human-written examples

Who's to say for certain?

The Guardian

Who can say for certain?

The Guardian - Film

He couldn't say for certain.

The Guardian

I cannot say for certain.

The Guardian

It's hard to say for certain.

Harvard Business Review

Who can ever say for certain?

The Guardian - Books

But you cannot say for certain.

The Guardian

I am sorry I cannot say for certain.

Yale University

"But I guess I can't say for certain".

The New Yorker

— though you really couldn't say for certain what.

The New Yorker

Nobody would say for certain where he was.

The New Yorker

Expert writing Tips

Best practice

Pair the phrase with conditional markers like "hard to" or "difficult to" to soften a lack of information without appearing ignorant.

Common error

Do not insert an article between the preposition and the adjective, as in "say for a certain". The phrase is a fixed idiomatic expression, and adding "a" makes it grammatically incorrect and disrupts its natural flow.

Linguistic Context

The phrase "say for certain" functions as an idiomatic verbal construction where the prepositional phrase "for certain" serves as an adverbial modifier to the verb "say". According to Ludwig, this structure is frequently utilized to denote epistemic modality—specifically, the degree of commitment a speaker has toward the truth of a proposition. It is most often found in negative or interrogative contexts to highlight a lack of absolute verification.

Expression frequency: Very common

Frequent in

News & Media

70%

Science

15%

Formal & Business

10%

Less common in

Academia

3%

Encyclopedias

1%

Wiki

1%

Ludwig's WRAP-UP

In summary, "say for certain" is a highly reliable and grammatically correct idiomatic phrase used to express the limits of knowledge or confirmation. Ludwig AI highlights its prevalence in high-authority news outlets like The New York Times and The Guardian, where it frequently appears in negative constructions such as "cannot say for certain" or "hard to say for certain". This usage helps writers maintain an objective tone by hedging claims that lack absolute proof. While synonyms like "say for sure" are common in casual speech, "say for certain" remains the preferred choice for professional, academic, and journalistic writing. Its structure is stable, though writers should be careful not to insert unnecessary articles or use incorrect prepositions that could diminish its idiomatic impact.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

say for sure

Uses a more colloquial adjective but is functionally identical in meaning.

tell for certain

Replaces the verb of communication to focus on the act of distinguishing or identifying a fact.

state definitively

Increases formality and implies a more authoritative or final declaration.

know for certain

Shifts the focus from external communication to the internal state of knowledge.

confirm with certainty

Adds a layer of verification, suggesting that the fact has been checked against evidence.

verify for certain

Emphasizes the process of proving something to be true.

declare with certainty

Suggests a formal or public announcement of a known fact.

state for a fact

Uses a more emphatic noun-based construction to emphasize objectivity.

establish beyond doubt

A much stronger alternative used when the evidence is absolute.

vouch for

Focuses on personal guarantee or testimony rather than general knowledge.

FAQs

How to use "say for certain" in a sentence?

You can use it to express the limits of your knowledge, for example: "At this stage, we cannot say for certain whether the project will be successful." It is often preceded by modal verbs like "can" or "could".

What is a more formal alternative to "say for certain"?

If you need a more formal tone, you can use "state definitively", "confirm with absolute certainty", or "ascertain".

Which is correct, "say for certain" or "say for sure"?

Both are grammatically correct, but "say for certain" is generally considered more appropriate for professional writing, while "say for sure" is more common in spoken English.

Can "say for certain" be used in positive sentences?

Yes, though it is less common. You might say, "One thing we can say for certain is that the climate is changing." However, it is most frequently used with negatives like "no one can" or "hard to".