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Is It Correct to Say, “The Reason Why”?

Some phrases become a part of long-running grammatical and acceptability debates despite overwhelming popular usage in writing and speech. The reason why they end up there can be one of many. Speaking of which, is it correct to say, “The reason why”?

It is correct to say “the reason why.” “Why” is the relative adverb that connects the noun “reason” to an adjectival clause that provides the necessary explanation or reason. 

Read on as we explore the phrase “the reason why” in-depth, including its meaning, usage, and other options for it. In addition, we will look at redundancies in the English language and when and how to avoid using them.

What Does “The Reason Why” Mean?

“The reason why” is a construct to help the speaker or writer provide an explanation or reason for something, be it an event or behavior. 

We can better understand this phrase by looking at the definitions of both “reason” and “why” separately. 

“The Reason”

“Reason” is a noun and refers to a statement or fact that explains why something happens or what causes it to happen. In other words, it provides an explanation or motive. 

As a noun, it also refers to the ability to think rationally and make sound judgments. We also use “reason” as a verb to describe the act of using the faculty of reason (source).


“Why” takes on various roles in a sentence based on its use. As an adverb and even as a conjunction, it essentially means “for what cause, reason, or purpose.” We can also use “why” as a noun, as in “the hows and whys of life.”

“The Reason Why”

“Why,” when we use it with “reason,” functions informally as a conjunction or relative adverb and means “reason for which” (source). 

For example, we can use “reason why” instead of “reason for which” as in the below example:

The reason why he left the job was that he got a better offer. (“why” replacing “for which”)

Of course, such sentences make complete sense even when we remove “why,” as we can see below:

The reason he left the job was that he got a better offer. (skipping both “why” and “for which”)

So why use “why”? The answer is that sometimes it helps add emphasis and rhythm to the sentence; it even makes it sound more natural. 

In some instances, we use the verb form of the word “reason,” in which case, “why” takes on its adverbial role, as in Tennyson’s famous lines from The Charge of the Light Brigade below:

“Theirs not to reason why, / Theirs but to do and die.”

Is It Grammatically Correct to Say “The Reason Why”?

While it is true that using both words together is kind of redundant, there is nothing wrong with either. It is, at its worst, a mild redundancy and, at its best, helps provide greater emphasis (source). 

Note that we can write sentences using “the reason why” in a few different ways while remaining grammatically correct and retaining the meaning, as we can see below:

  • The reason why these cakes are so expensive is they are custom-made.
  • The reason that these cakes are so expensive is they are custom-made.
  • The reason these cakes are so expensive is they are custom-made.
  • These cakes are so expensive because they are custom-made.

However, we should generally avoid using “because” with “the reason why,” as in the following sentence: 

The reason why these cakes are so expensive is because they are custom-made.

It makes a sentence of this length sound awkward and wordy when you use “reason why” and “because” together.

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Is It “Reason That” or “Reason Why”?

Both “reason that” and “reason why” are correct. In fact, we can substitute “why” with “that” after “reason,” or vice versa, without losing its meaning. We can also skip “that” and “why” completely, as we have seen earlier (source).

However, there are certain instances where it is better to use one of these options over skipping them and preferable to use either “why” or “that.” We will look at each of these with examples now.

“Reason That” vs. “Reason Why”

As we mentioned earlier, we use “reason why” before a relative clause. We can substitute “why” with “that” in almost all cases. While “reason that” is more formal than “reason why,” we use it less often.

Say you are talking to a friend about why another friend wasn’t at a party. You would say something like below:

  • The reason why she wasn’t at the party was that she missed the train. 

However, if you are providing a similar explanation to your boss about a colleague’s absence at a party, you might prefer to use “that” instead:

  • The reason that she wasn’t at the party was that she missed the train. 

You can choose to omit “why” or “that” completely, as in:

  • The reason she wasn’t at the party was that she missed the train. 

We do not use “that” with the plural “reasons.” Instead, we use “why,” or we can choose to skip it, as below:

  • There were several reasons why she wasn’t at the party. 
  • There were several reasons she wasn’t at the party. 

Note that while the above uses examples in speech, we can also apply these rules in written language.

So, to sum it up:

First, informal writing uses “reason why” or simply “reason” — for example, an email to a friend or fictional writing.

Second, formal writing will use “reason that” or skip “that” and use only the word “reason” — for example, official emails or academic essays.

Before you switch “reason why” with “reason that,” remember “reason that” can sometimes sound awkward, so use your best judgment in each case.

Understanding How and When to Use “The Reason Why”

Let us now try to understand the many ways we can use “the reason why,” as well as when to use it or not, as the case may be. We will also explore other options for this construct. 

How Do You Use “The Reason Why”?

We use “the reason why” before a relative clause that provides the actual reason or explanation for something — an event or behavior. We can use the construct “the reason why” as part of a sentence in various ways. 

It can begin a sentence as in the following example:

  • The reason why Jack failed the test is that he skipped his classes. 

In this case, the actual reason why Jack failed his test — he skipped his classes — follows the noun “reason.” 

Since this sentence already includes the explanation, it does not need additional context or information and can stand independently. This sentence tells us that a) Jack failed the test and b) he failed because he skipped his classes.

Or we could also use it within the sentence, as we’ve shown below:

Jack skipped most of his classes. That is the reason why he failed the test. 

There are many reasons why Jack failed the test. One of them is that he skipped classes. 

Note that in these sentences above, we use the sentence containing “reason why” in combination with others that give the required explanation or information. We can add this additional context in a separate sentence(s) either before or after the one with “reason why,” depending on our preference.

Using “The Reason Why” in a Full Sentence

Let’s look at a few more examples to understand better how we can use “the reason why.”

  • I don’t understand the reason why all of them failed the exam. 
  • She practiced diligently every day. That is the reason why she performed flawlessly.
  • Do you know the reason why the school is closed today?
  • The reason why I treasure this book is that my dad gifted it to me. 

When Can You Use “The Reason Why”?

We use “the reason why” in informal writing to introduce defining relative clauses instead of “for which.” We also use it in situations when we want to emphasize the clause following “why.” Also, remember that we can use “why” with the plural “reasons” and not “that.” 

Remember that “reason why” is not incorrect, and in some cases, it helps to avoid awkwardness in writing or speech. Let us consider the following sentence:

  • The reason why he quit his well-paying job is that he didn’t enjoy it. 

Replace “why” with “that,” and we get:

  • The reason that he quit his well-paying job is that he didn’t enjoy it. 

As you can see, this sentence sounds awkward due to the presence of more than one “that,” and the option with “why” sounds smoother.

Now, let us remove the “why,” and we get:

  • The reason he quit his well-paying job is that he didn’t enjoy it. 

While omitting the “why” results in the most concise option, we also can see that the “why” adds a pause to the sentence. This pause helps add emphasis and meaning, so we can decide whether to retain or skip the redundant “why” on a case-by-case basis depending on our needs. 

In What Context Can You Use “The Reason Why”?

As we have already discussed, we can use “the reason why” in many situations, including informal speech or writing, or when adding emphasis or a pause before the relative clause.

When Not to Use “The Reason Why”?

Try to avoid using it in formal writing or where the writing needs to be crisp. Still, while it is certainly not incorrect and is just slightly redundant, using “the reason why” indicates some informality and wordiness.

Also, don’t use it with “is because,” as in the below example:

  • The reason why he came home is because he missed everyone.

Instead, simply say, “He came home because he missed everyone.”

What Can You Use Instead of “The Reason Why”?

Depending on usage (formal or informal) and requirements, such as the need for emphasis or crispness, we can use the following alternatives for “the reason why.”

Consider the sample sentence with “the reason why” and sentences with the alternatives for “the reason why” below.

  • The reason why the restaurant failed was its bad location.
  • The reason that the restaurant failed was its bad location.
  • The reason for which the restaurant failed was its location.
  • The restaurant failed because of its bad location.
  • The restaurant failed due to its bad location.
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Redundancies in English: How and When to Avoid Them

Redundancies are generally repetitions of words or phrases which lead to excessive wordiness in our speech or writing. The English language is full of redundancies, and because they are all around us, it is often easy to overlook them. For example, “pick and choose,” “end result,” “unexpected surprise,” or “forever and ever.” 

But does something being a redundancy mean that we should eliminate it completely? The answer is not always. 

Sometimes, redundancy helps clarify things, place emphasis, or help ensure that we do not miss anything important, especially when imparting new, complex, or critical information or ideas. Most often, however, redundancy can confuse and completely obscure the meaning.

Therefore, we should focus both on the meaning and impact that any redundancy lends to the sentence before deciding whether to keep it or not. This article was written for

In the end, what matters is better writing, which makes an impact; and if that extra word or phrase helps emphasize or clarify ideas, we should go ahead and use it. Check out our article “Is It Correct to Say “Repeat Again”?” for more on redundancies.

Final Thoughts

As we have seen in this article, “the reason why” is only harmlessly redundant, and in fact, can help in many instances to provide a pause, add emphasis, and simply make a sentence more natural. 

We need to use our best judgment each time we use “the reason why” or any other redundant phrases. Reading sentences out loud helps, and soon, we will learn and know the reason why, how, where, and when it is okay or not okay to use certain words and phrases.