I didn't know that

USAGE SUMMARY

The sentence "I didn't know that" is correct and usable in written English.
You can use it whenever you need to express surprise or lack of knowledge about something. For example: "I didn't know that elephants have an excellent memory."

✓ Grammatically correct

News & Media

Human-verified examples from authoritative sources

Exact Expressions

59 human-written examples

But I didn't know that.

The New York Times - Arts

I wish I didn't know that.

The Economist

I didn't know that existed".

The Guardian

"I didn't know that was possible.

The New York Times - Sports

I'll admit, I didn't know that.

The Guardian - Sport

Hey man, I didn't know that.

The Guardian - Music

MA: I didn't know that.

TechCrunch

I didn't know that makes me foolish.

TechCrunch

Lindsey: I didn't know that.

Los Angeles Times

But you see, I didn't know that.

Wikipedia

(Laughs) I didn't know that.

Huffington Post

Expert writing Tips

Best practice

Use "I didn't know that" to express surprise or acknowledge new information in conversations or informal writing. It shows active listening and engagement.

Common error

Avoid using "I didn't know that" sarcastically or dismissively. Ensure your tone is genuine to prevent miscommunication, as it can sometimes imply criticism of the speaker for not informing you earlier.

Linguistic Context

The phrase "I didn't know that" functions as an acknowledgment of new information. It expresses a lack of prior knowledge and often conveys surprise or mild astonishment. As Ludwig examples show, it's a common way to react to something previously unknown.

Expression frequency: Very common

Frequent in

News & Media

78%

Science

10%

Formal & Business

6%

Less common in

Wiki

3%

Academia

2%

Encyclopedias

1%

Ludwig's WRAP-UP

In summary, the phrase "I didn't know that" is a common and grammatically correct way to express surprise or a lack of prior knowledge about something. Ludwig AI confirms its validity and frequent usage across various contexts, particularly in News & Media. While it's generally neutral in register, being mindful of tone is important to avoid misinterpretations. Exploring alternatives like "I wasn't aware of that" or "that's news to me" can add variety to your communication. Using this phrase effectively involves genuine expression and consideration of the conversational context.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

I wasn't aware of that

Substitutes "didn't know" with "wasn't aware", indicating a lack of prior knowledge.

I had no idea

Expresses a stronger sense of surprise and complete lack of knowledge.

That information is new to me

Focuses on the novelty of the information to the speaker.

That's news to me

Replaces the personal pronoun and verb with a more direct acknowledgment of receiving new information.

I'm surprised to hear that

Highlights the speaker's surprise upon hearing the information.

That's something I just learned

Emphasizes the recent acquisition of the information.

I've just found that out

Emphasizes the immediacy of discovering the information.

I wasn't informed about that

Suggests that the speaker should have been told the information earlier.

So that's why

Indicates a realization or understanding of something previously unclear.

You learn something new every day

A more general expression of surprise and acceptance of new information.

FAQs

How can I use "I didn't know that" in a sentence?

You can use "I didn't know that" to express surprise or acknowledge new information. For example, "You said he was a doctor? "I didn't know that"!"

What are some alternatives to "I didn't know that"?

Alternatives include "I wasn't aware of that", "that's news to me", or "I had no idea", depending on the level of surprise or emphasis you want to convey.

Is it correct to say "I didn't knew that"?

No, "I didn't knew that" is grammatically incorrect. The correct form is ""I didn't know that"", using the base form of the verb "know" after "did".

When is it inappropriate to use "I didn't know that"?

It might be inappropriate if you were expected to know the information, or if you want to avoid sounding dismissive. In such cases, consider phrasing your response more diplomatically.