That's the reason why

USAGE SUMMARY

The phrase "That's the reason why" is correct and usable in written English
It can be used to explain or justify a statement or action. Example: "I decided to take the day off; that's the reason why I won't be at the meeting."

✓ Grammatically correct

News & Media

Science

Formal & Business

Human-verified examples from authoritative sources

Exact Expressions

56 human-written examples

In fact, that's the reason why reflection holograms are named to be wavelength-selective.

Journal of the European Optical Society-Rapid Publications

"In all seriousness, that's the reason why we wanted to bring Mike back here.

Los Angeles Times

"That's the reason why they're there.

The New York Times

"That's the reason why we advertise it".

The New York Times

"That's the reason why I love it.

The New York Times

"That's the reason why Russia has another article," she said.

Independent

That's the reason why I'm able to score big runs".

Independent

That's the reason why he's as good as he is".

The New York Times - Sports

"That's the reason why we got beat up".

The New York Times - Sports

"That's the reason why we lost," Holik said.

The New York Times - Sports

That's the reason why they call him The Answer.

The New York Times - Sports

Expert writing Tips

Best practice

In formal academic papers where brevity is prized, consider shortening it to "That's why" or using "For this reason" to avoid the slight redundancy of 'reason' and 'why'.

Common error

Avoid saying "the reason is because". Since 'reason' already implies a cause, follow it with a 'that' clause or use "That's the reason why" to maintain grammatical clarity.

Linguistic Context

The phrase "That's the reason why" serves as a causal connector that introduces a relative clause. It functions as a bridge between an established fact and the explanation for that fact. According to Ludwig AI, it is a correct and usable structure for justifying actions or statements.

Expression frequency: Very common

Frequent in

News & Media

65%

Science

20%

Formal & Business

15%

Less common in

Social Media

5%

Wiki

3%

Reference

2%

Ludwig's WRAP-UP

In conclusion, "That's the reason why" is a robust and versatile phrase used to establish causality across various registers. Ludwig AI confirms its correctness, noting its effectiveness in explaining or justifying statements. While linguistic purists sometimes debate the necessity of using both 'reason' and 'why' together, the phrase remains a staple in professional journalism and scientific writing. It is particularly useful when the writer wishes to emphasize the 'reason' specifically. For those seeking greater brevity, alternatives like "that's why" or "for this reason" are excellent substitutes that maintain the same logical connection.

More alternative expressions

Phrases that express similar concepts, ordered by semantic similarity:

That's why

Removes the word 'reason' for a more concise and direct explanation.

This is why

Uses 'this' to refer to a more immediate or specific preceding fact.

For that reason

A more formal and structurally standard way to introduce a consequence.

That explains why

Explicitly identifies the preceding information as the explanation for the following clause.

Which is why

Connects the cause and effect within a single sentence as a non-restrictive relative clause.

Because of that

Utilizes a prepositional phrase to link the reason to the result.

That is the cause of

Focuses more narrowly on direct causation rather than general reasoning.

Hence

A very formal and succinct transition used primarily in academic or technical writing.

Therefore

A classic adverbial conjunction indicating a logical conclusion.

Which accounts for

A formal alternative often used in data analysis or scientific reporting.

FAQs

How to use "That's the reason why" in a sentence?

You can use it to link a fact to its explanation, for example: "The team practiced every day; "That's the reason why" they won the championship."

What can I say instead of "That's the reason why"?

You can use more concise alternatives like "that's why", "for that reason", or "this explains" depending on your desired tone.

Is "That's the reason why" grammatically correct?

Yes, it is widely accepted and correct. While some stylists consider it slightly redundant because 'reason' and 'why' convey similar meanings, it is standard in modern English and frequently appears in reputable publications like The New York Times.

What is the difference between "That's the reason why" and "That's why"?

The primary difference is length and emphasis; "that's why" is shorter and more direct, whereas "That's the reason why" adds a slight rhythmic emphasis to the word 'reason'.