When I started editing professionally, I noticed how often people said “hence why” in speech and even formal writing. It’s a common but misunderstood expression, and many don’t realize it’s considered a grammar error. Editors, teachers, and most style guides strongly recommend avoiding it.
The redundancy comes from using two words—hence and why—that serve the same purpose. To be more precise, choose one or the other. Saying “hence” already gives the meaning or context of the reason, so adding “why” makes it technically incorrect.
If you aim for clarity, using a cleaner, more modern form is best. Expressions evolve, and improving usage is part of writing smarter. Language should help us communicate better, not confuse our message. In formal or casual settings, the goal is to sound smarter and be clearly understood. That’s why avoiding confusing structures like this matters. Choosing stronger structure and tone doesn’t mean sounding robotic—it just means respecting the form and being understood.
What Does “Hence Why” Actually Mean?
At first glance, “hence why” seems harmless. It’s often used to explain a reason or a cause. For example:
“He missed the deadline, hence why the project was delayed.”
In that sentence, “hence why” appears to mean “that’s the reason.” But here’s the problem: both “hence” and “why” convey the idea of reason. So putting them together is redundant—like saying “reason why,” or worse, “reason the reason why.”
Let’s break it down:
- Hence = for this reason, therefore, or as a result
- Why = the reason
Put together: “Hence why” = for this reason the reason, which is unnecessarily repetitive.
Is “Hence Why” Grammatically Incorrect?
Technically, yes. “Hence why” is a redundant phrase and not considered correct in formal or academic writing.
According to Garner’s Modern English Usage, “hence” already implies causality. Adding “why” is both tautological and stylistically weak.
What Language Experts Say:
| Source | Comment on “Hence Why” |
| Garner’s Usage Guide | “Redundant. Avoid in academic or professional contexts.” |
| Chicago Manual of Style | “Prefer precise, non-repetitive forms.” |
| Merriam-Webster | “Hence = ‘for this reason.’ Adding ‘why’ is unnecessary.” |
| Oxford English Dictionary | Does not list “hence why” as a standard idiom. |
So while it’s often heard in spoken English, it’s not something you should write in an essay, research paper, report, or resume.
What “Hence” Really Means in American English
Understanding “hence” starts with its function. It’s an adverb, not a conjunction or preposition. It means:
- As a result of this
- From this place or time
- Therefore
Common Correct Usages:
- “The roads were icy; hence the delay.”
- “He was underqualified, hence he wasn’t hired.”
- “The factory was built in 1910; hence its historical value.”
It’s typically used in formal writing, and it’s especially common in legal, academic, and scientific texts.
Fun fact: “Hence” has roots in Middle English and originally meant “from here.” Over centuries, it took on its causal meaning.
“Hence Why” vs. “That’s Why”: Understanding the Difference
Here’s where many writers get tripped up. “That’s why” is grammatically correct and idiomatic in modern English. It clearly connects cause and effect without redundancy.
Comparison Table:
| Phrase | Correct? | Formality | Usage |
| Hence Why | ❌ No | Formal contexts – avoid | Sounds verbose and redundant |
| That’s Why | ✅ Yes | Neutral/informal | Conversational, clear |
| Hence | ✅ Yes | Formal | Used in academic/professional settings |
Use “that’s why” for casual and spoken English.
Use “hence” for formal writing.
Avoid using “hence why” altogether.
Examples of Proper “Hence” Usage
Let’s get real. These are the kinds of sentences that work—and don’t:
✔ Correct:
- “The battery was faulty; hence, the recall.”
- “He didn’t attend the meeting, hence the confusion.”
- “She lived overseas for five years, hence her fluency in French.”
✘ Incorrect:
- “She was tired, hence why she slept early.”
- “The team lost, hence why the coach was frustrated.”
Instead of those awkward constructions, rewrite like this:
“She was tired, hence she slept early.”
“The team lost; that’s why the coach was frustrated.”
What to Say Instead of “Hence Why”
When in doubt, replace “hence why” with one of these clearer alternatives:
Better Alternatives:
- “Hence”
- “That’s why”
- “Therefore”
- “Thus”
- “As a result”
- “For this reason”
Choosing the Right One:
| Phrase | Best For | Example |
| Hence | Formal writing | “The results were inconclusive, hence the need for more research.” |
| That’s why | Everyday conversation | “He forgot his ID. That’s why he wasn’t allowed in.” |
| Therefore | Academic writing | “No evidence supports the claim; therefore, the hypothesis is rejected.” |
| Thus | Scientific reports | “The sample was contaminated. Thus, the test was void.” |
| As a result | Narrative, business writing | “Sales dropped. As a result, the budget was cut.” |
“Hence,” “Therefore,” or “Thus”? Clarifying the Confusion
These words are often used interchangeably, but they’re not always perfect substitutes. Here’s how they differ:
| Word | Tone | Best Used In | Example |
| Hence | Formal, logical | Essays, academic papers | “He was late, hence the penalty.” |
| Therefore | Logical, formal | Legal, academic writing | “All elements were present; therefore, the reaction occurred.” |
| Thus | Neutral-formal | Reports, documentation | “Data was skewed. Thus, we revised our method.” |
Tip: “Hence” is a little older in feel. “Therefore” sounds more modern in academia.
Grammar Evolution and Why Some “Wrong” Phrases Stick
Language isn’t static. What was “wrong” 100 years ago might be acceptable today—and vice versa. So why is “hence why” still around?
Here’s why:
- Redundant phrases become normalized through media and casual speech
- People mimic others, especially public figures, authors, and bloggers
- Our brains prioritize comprehension over precision in daily use
But just because a phrase feels right doesn’t mean it is right.
“We tend to write how we speak. But the page has higher standards than conversation.” — Steven Pinker
Common Redundant Phrases Like “Hence Why” to Avoid
“Hence why” isn’t the only culprit. Here are others to watch for:
| Redundant Phrase | Better Version |
| “Close proximity” | “Proximity” |
| “Past history” | “History” |
| “Final outcome” | “Outcome” |
| “Advance warning” | “Warning” |
| “End result” | “Result” |
These extra words add clutter, not clarity.
Real-World Impact: Why Grammar Precision Matters
In College:
Professors expect clean, professional writing. Using phrases like “hence why” might not get you failed, but it could ding your credibility.
In Work:
Imagine submitting a project proposal filled with fluff. Your reader may question your attention to detail—and your authority.
In Communication:
Poor grammar clouds your message. Precise grammar amplifies clarity and influence.
Clear writing = clear thinking. And clear thinking builds trust.
Mini-Quiz: Can You Spot the Error?
Test your grammar skills. Which of these sentences is incorrect?
- He missed the train, hence the delay.
- The ice melted; that’s why the street flooded.
- She failed to submit her application, hence why she was rejected.
- The experiment failed. Therefore, we started over.
Answer: Sentence 3 is incorrect. It should be:
“She failed to submit her application, hence she was rejected.”
or
“She failed to submit her application. That’s why she was rejected.”
Conclusion: So, Should You Ever Use “Hence Why”?
If you’re writing an essay, professional email, or academic article, skip “hence why.” It’s redundant, unnecessary, and can undercut your credibility.
Instead:
- Use “hence” in formal writing
- Use “that’s why” in everyday conversation
- Use “therefore” and “thus” when you want to sound clear and precise
Stay sharp. Avoid fluff. Your readers—and grades—will thank you.
Additional Resources
Want to dig deeper into grammar and writing clarity? Check out these helpful links:
- Chicago Manual of Style
- Purdue OWL Grammar Guide
- Merriam-Webster Dictionary
- APA Style Guide
Conclusion
Using “hence why” may sound natural in everyday speech, but it’s grammatically incorrect and redundant in formal contexts. Both hence and why explain a reason, so using them together repeats the same idea. If you want to sound clear, precise, and professional, choose one word that fits your sentence best.
Whether you’re writing an article, an email, or a school paper, small changes like this can greatly improve how your message is received. When in doubt, simplify your language—it helps you communicate smarter.
FAQs
1. Is “hence why” ever acceptable in writing?
In informal speech, many people use it without issue. But in formal writing, it’s considered redundant and should be avoided.
2. What can I use instead of “hence why”?
You can use either “hence” or “why” alone. For example:
- “He failed the exam, hence the disappointment.”
- “That’s why he was upset.”
3. Why is “hence why” considered redundant?
Because both words explain a reason. Using them together repeats the same meaning.
4. Will using “hence why” make my writing look bad?
It might not seem wrong in casual use, but editors and teachers may mark it as a grammar mistake in professional or academic writing.
5. Is “hence” outdated or old-fashioned?
No, “hence” is still used in modern English, especially in formal or academic writing. Just make sure it fits the tone and structure of your sentence.
