i know for sure

USAGE SUMMARY

The phrase "I know for sure" is correct and usable in written English.
It can be used when expressing certainty or confidence about a statement or belief. Example: "I know for sure that we will succeed in this project."

✓ Grammatically correct

News & Media

Human-verified examples from authoritative sources

Exact Expressions

59 human-written examples

"Now I know for sure".

The New York Times

"That I know for sure.

The New York Times - Sports

That's all I know for sure.

The Guardian

How can I know for sure?

The New Yorker

That much I know for sure.

The Guardian - Lifestyle

Do I know for sure that this is the truth?

The New York Times

That is something that I know for sure.

The New Yorker

I know for sure everybody has to go".

The New York Times

"I know for sure the money is there," said Lloyd.

The Guardian - Sport

I know for sure I wouldn't do it better.

The Guardian - Lifestyle

"There are two things about human beings that I know for sure," he told me.

The New Yorker

Expert writing Tips

Best practice

When using "i know for sure", ensure that what follows is based on solid evidence or strong personal conviction to maintain credibility.

Common error

Avoid using "i know for sure" when you lack concrete evidence or a strong basis for your claim. Overusing the phrase without proper justification can undermine your credibility.

Linguistic Context

The phrase "i know for sure" functions as an emphatic declarative. It asserts a statement with a high degree of certainty. Ludwig AI confirms its common usage in various contexts, reinforcing its function as a strong declaration.

Expression frequency: Very common

Frequent in

News & Media

72%

Science

15%

Formal & Business

8%

Less common in

Encyclopedias

0%

Wiki

0%

Reference

0%

Ludwig's WRAP-UP

In summary, the phrase "i know for sure" is a common and grammatically correct expression used to convey certainty and confidence. As Ludwig AI confirms, this phrase is widely used across various contexts, particularly in news and media. When writing, ensure that your confidence is well-founded with evidence or conviction to maintain credibility. While versatile, be mindful of the audience and context, as overuse without justification can weaken your message. Alternatives such as "i am certain" or "i have no doubt" can be used for variety. With a neutral register, "i know for sure" serves as a powerful tool for persuasive and assertive communication.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

i'm absolutely certain

Adds "absolutely" to increase the degree of certainty.

i am certain

Replaces "know" with "am certain", emphasizing the speaker's confidence.

i am positive

Similar to "i am certain", but may imply slightly less formal certainty.

i have no doubt

Emphasizes the absence of doubt in the speaker's mind.

i am convinced

Suggests the speaker has been persuaded and is now certain.

i am sure of it

Adds "of it" for emphasis, clarifying the object of certainty.

it's a certainty

Shifts the focus to the event being certain rather than the speaker's knowledge.

without a doubt

Similar to "i have no doubt", but expressed as an adverbial phrase.

i can guarantee

Implies a strong promise or assurance based on certainty.

i can assure you

A more formal way of conveying certainty, often used in professional contexts.

FAQs

How can I use "i know for sure" in a sentence?

You can use "i know for sure" to express certainty about something. For example, "I know for sure that it will rain tomorrow".

What can I say instead of "i know for sure"?

You can use alternatives like "i am certain", "i am positive", or "i have no doubt" depending on the context.

Which is correct, "i know for sure" or "i know it for sure"?

"I know for sure" is the more natural and commonly used phrasing in English. "I know it for sure" is less idiomatic.

What's the difference between "i think" and "i know for sure"?

"I think" expresses an opinion or belief with some uncertainty, while "i know for sure" conveys a high degree of confidence and certainty.