Both “which” and “that” are correct, but they are used in different situations. The difference depends on whether the information is essential to the meaning of the sentence.
Many people mix up which and that because they both introduce extra information about a noun. In everyday speech, people often use them interchangeably, but formal writing usually follows a simple rule.
In this article, you’ll learn the difference between which and that, when to use each one, common mistakes to avoid, and an easy trick to remember the rule.
Quick Answer
Use “that” for information that is necessary to identify the person or thing you are talking about.
Use “which” for extra information that could be removed without changing the main meaning of the sentence. This information is usually set off by commas.
Examples:
- The book that I borrowed is on the table.
- The book, which I borrowed yesterday, is on the table.
Which vs That: Main Difference
| Word | Meaning | Correct? | Best Used For | Example |
| That | Introduces essential information | Yes | Identifying the exact person or thing | The car that is parked outside is mine. |
| Which | Introduces extra, non-essential information | Yes | Adding additional details | My car, which is blue, is parked outside. |
What Does Which Mean?
Which is a relative pronoun used to add extra information about a noun. The sentence still makes sense if this information is removed.
In formal writing, which is usually preceded by a comma.
Examples
- My laptop, which is five years old, still works well.
- The hotel, which overlooks the beach, was beautiful.
- Sarah bought a dress, which was on sale.
- The meeting, which lasted two hours, ended successfully.
- This cake, which my grandmother baked, tastes amazing.
What Does That Mean?
That is a relative pronoun used to introduce essential information. Without this information, the sentence would not clearly identify what you mean.
Unlike which, that is generally not preceded by a comma.
Examples
- The student that won the prize worked very hard.
- I need the file that you emailed yesterday.
- The shoes that fit me are expensive.
- The restaurant that serves Italian food is nearby.
- She found the keys that she had lost.
How to Use Which or That
A simple rule can help you choose the right word.
Use that when the information is necessary.
Without it, the meaning changes.
Correct:
- The phone that has a broken screen belongs to Alex.
- I want the book that you recommended.
Use which when the information is extra.
If you remove it, the main sentence still makes sense.
Correct:
- My phone, which has a broken screen, still works.
- This book, which was published last year, became a bestseller.
Avoid These Mistakes
Incorrect:
- The car, that is parked outside, is mine.
Correct:
- The car that is parked outside is mine.
Incorrect:
- My car which is blue is parked outside. (Formal writing)
Correct:
- My car, which is blue, is parked outside.
Note: In everyday conversation, native speakers sometimes use which where formal grammar would prefer that. The distinction above is the standard guideline for formal writing.
Where to Use Which or That
School Writing
Follow the standard rule:
- That for essential information.
- Which for extra information with commas.
Formal Writing
Using the distinction between which and that makes your writing clearer and more precise.
Emails
The same rule applies, although informal emails may be more flexible.
Everyday Conversation
People often use both words naturally without worrying about the formal distinction. The meaning is usually clear from context.
Messages
In texts and chats, people commonly mix the two, but using them correctly improves clarity.
Professional Communication
Reports, business emails, and official documents usually follow the standard grammar rule.
American English
American style guides strongly recommend:
- That for essential clauses.
- Which for non-essential clauses.
British English
British English is generally more flexible. Writers sometimes use which in places where American English would prefer that, although the standard distinction is still widely accepted.
Other Regions
Countries such as Canada, Australia, India, Pakistan, and New Zealand generally follow British English conventions but often accept the same distinction used in formal writing.
Why People Get Confused
There are several reasons why people confuse which and that.
- Both words introduce relative clauses.
- Both refer back to a noun.
- Native speakers often use them interchangeably in conversation.
- The punctuation rule with commas is easy to overlook.
- American and British writing styles are not always identical.
Common Mistakes to Avoid
Wrong:
The movie, that we watched, was exciting.
Correct:
The movie that we watched was exciting.
Explanation: The clause identifies which movie.
Wrong:
My brother that lives in London is visiting.
Correct:
My brother, who lives in London, is visiting.
Explanation: For people, who is generally preferred over that in formal writing when adding extra information.
Wrong:
My bike which I bought last year was stolen.
Correct:
My bike, which I bought last year, was stolen.
Explanation: The phrase adds extra information and should be separated by commas.
Wrong:
I need the notebook, which is on the desk.
Correct:
I need the notebook that is on the desk.
Explanation: The clause identifies which notebook.
Real-Life Examples
Meeting
Please send the report that we discussed yesterday.
School
The teacher assigned the project that is due next week.
Travel
Our hotel, which was close to the station, was very convenient.
Work
The employee that solved the problem received praise.
Message
I loved the gift, which arrived this morning.
Conversation
The café that serves fresh coffee is always busy.
Booking
The room that we reserved has a sea view.
Social Situation
Emma’s party, which was held on Saturday, was a lot of fun.
Easy Trick to Remember
Think of this simple rule:
- That = Needed to identify.
- Which = Extra information in commas.
If you can remove the information without changing the main meaning, use which.
Mini Quiz
1. Which sentence is correct?
A. The book that I borrowed is interesting.
B. The book, that I borrowed, is interesting.
Answer: A
2. Fill in the blank:
The laptop _____ has a cracked screen belongs to me.
Answer: that
3. Fill in the blank:
My laptop, _____ I bought last year, still works perfectly.
Answer: which
4. True or False:
Extra information is usually introduced by which.
Answer: True
5. Which word usually does not follow a comma?
Answer: that
6. Which sentence uses the correct punctuation?
A. My car which is red is parked outside.
B. My car, which is red, is parked outside.
Answer: B
Related Confusing Words
- who or whom
- who or that
- its or it’s
- your or you’re
- there or their
- affect or effect
- farther or further
- then or than
FAQs About Which or That
Is which correct?
Yes. Use which for extra, non-essential information, usually with commas.
Is that correct?
Yes. Use that for essential information needed to identify the noun.
What is the difference between which and that?
That introduces necessary information. Which introduces additional information that can usually be removed.
Which one should I use?
Use that when the information is essential. Use which when it simply adds extra detail.
Is this rule formal or informal?
The distinction is most important in formal writing. Everyday speech is often more flexible.
Conclusion
Both which and that are correct, but they serve different purposes. Use that when the information is necessary to identify someone or something. Use which when you are adding extra information, and place that information between commas. Following this simple rule will make your writing clearer, more accurate, and easier to understand.
Ava Collins is a passionate writer who enjoys turning everyday ideas into clear, engaging, and helpful content. She loves exploring language, culture and meaningful stories that connect with readers. Ava is also the fictional author of Beneath the Silver Maple and The Last Lantern of Willow Cove. When she’s not writing, she enjoys reading, traveling and finding inspiration in ordinary moments.