That or Which | The Simple Grammar Choice That Can Change Your Sentence

Last updated August 20, 2026 at 3:45 pm by info.myworkonline@gmail.com

I’ve seen how easily that or which can confuse even confident writers especially when one small word can change the meaning of a sentence. In this guide, I’ll break down the difference with clear rules and real examples, so you can choose the right word without second-guessing yourself. If you’re here wondering which one belongs in your sentence, you’re in the right place.

So, when should you use “that” or “which”?
Use that for essential information and which usually introduces extra, nonessential information.

Quick Answer

Use that when the information after it is necessary to understand the sentence. Use which when the information is extra and can be removed without changing the main meaning. For example, “The book that I borrowed is overdue” means the borrowed book is overdue. “The book, which I borrowed, is overdue” means the book is overdue, and by the way, I borrowed it.

That vs Which: Main Difference

What Does That Mean?

That is a relative pronoun. It introduces a clause that is necessary to identify the noun you are talking about. Without this information, the sentence becomes unclear or changes meaning.

This essential information is called a restrictive clause. You cannot remove it from the sentence.

Examples:

1. “The laptop that has the blue sticker is mine.” (This identifies which laptop.)
2. “She adopted the dog that was rescued last week.” (This tells you which dog.)
3. “I need the recipe that uses honey instead of sugar.” (This specifies which recipe.)
4. “The students that finished their homework can leave early.” (This defines which students.)
5. “The movie that won the award was fantastic.” (This identifies the winning movie.)

What Does Which Mean?

Which is also a relative pronoun. It introduces a clause that adds extra, non-essential information about the noun. The sentence would still make perfect sense without this clause.

This extra information is called a non-restrictive clause. You can remove it, and the main meaning stays the same. In writing, which clauses are set off with commas.

Examples:

1. “My laptop, which has a blue sticker, is very fast.” (The sticker detail is extra.)
2. “The dog, which was rescued last week, loves to play.” (The rescue detail is extra.)
3. “The recipe, which uses honey instead of sugar, is my favorite.” (The honey detail is extra.)
4. “The students, which finished their homework, left early.” (The homework detail is extra.)
5. “The movie, which won the award, was fantastic.” (The award detail is extra.)

How to Use That or Which

Here is the simple rule to follow every time you write:

Use “that” when:

• The information is essential to identify the noun.
• There is no comma before the clause.
• You cannot remove the clause without losing meaning.

Example: “The shoes that I bought yesterday are already torn.” (This tells you which shoes.)

Use “which” when:

• The information is extra and not essential.
• There is a comma before the clause.
• You can remove the clause and the sentence still makes sense.

Example: “My shoes, which I bought yesterday, are already torn.” (The main point is that the shoes are torn; the purchase date is extra.)

Important Note About “That”

Never use a comma before that. The clause after that is always essential, so commas are not used.

• Correct: “The house that has a red door is for sale.”
• Incorrect: “The house, that has a red door, is for sale.”

Important Note About “Which”

Always use a comma before which when it introduces non-essential information.

• Correct: “The house, which has a red door, is for sale.”
• Incorrect: “The house which has a red door is for sale.” (This would imply that the house is identified by the red door, which is wrong if the red door is just extra.)

Where to Use That or Which

School Writing

Use that for essential details and which for extra comments. Teachers expect this distinction. “The experiment that failed taught us a lot” is correct because the failure is key.

Formal Writing

Follow the rule strictly. In business reports, academic papers, and official letters, using that and which correctly shows attention to detail.

Emails and Messages

In casual writing, people sometimes mix them up. However, using them correctly makes your writing clearer. “Please send the file that I asked for” is better than “the file which I asked for.”

Everyday Conversation

In speech, people often use which for everything. However, careful speakers use the rule to avoid confusion.

Professional Communication

In resumes, cover letters, and professional emails, correct usage matters. “The role that I applied for” is essential information about the role.

American vs British English

Both American and British English follow the same rule. There is no difference between the two forms of English here. Writers in both regions use that for essential clauses and which for non-essential clauses.

Why People Get Confused

People confuse that and which for several reasons.

First, both words refer to things or animals. They seem interchangeable at first glance. In speech, many people use which all the time, so they never learn the difference.

Second, some older grammar guides used which for both essential and non-essential clauses. This old rule is no longer common, but it still confuses some people.

Third, the comma rule is tricky. Many writers forget to add commas before which, so they end up using it incorrectly.

Fourth, non-native speakers often learn the words as synonyms. They are not synonyms, so this leads to mistakes.

Common Mistakes to Avoid

Mistake 1: Using “which” without commas

• Wrong: “The cake which I baked was delicious.”
• Correct: “The cake that I baked was delicious.” (If identifying the cake)
• Or: “The cake, which I baked, was delicious.” (If baking is extra)

Mistake 2: Using “that” for extra information

• Wrong: “The car, that I just washed, is already dirty.”
• Correct: “The car, which I just washed, is already dirty.”
• Explanation: “I just washed” is extra information, so use which with commas.

Mistake 3: Forgetting commas before “which”

• Wrong: “My phone which is new already has a scratch.”
• Correct: “My phone, which is new, already has a scratch.”
• Explanation: The newness is extra, so set it off with commas.

Mistake 4: Using “which” for people

• Wrong: “The teacher which I liked moved away.”
• Correct: “The teacher whom I liked moved away.” (Or “that” in informal speech)
• Explanation: Which is for things and animals, not people. Use who or whom for people.

Mistake 5: Overusing “which” in essential clauses

• Wrong: “The book which I read was boring.” (If the reading identifies the book)
• Correct: “The book that I read was boring.”
• Explanation: If “I read” is essential to know which book, use that.

Real-Life Examples

In a meeting:

“The proposal that we submitted last week was approved.” (Essential: which proposal?)

At school:

“My science project, which took three weeks to complete, won first place.” (Extra: the time is additional info)

At work:

“The client that called this morning wants a refund.” (Essential: which client?)

During travel:

“The hotel, which is near the beach, has great reviews.” (Extra: location is extra)

In a message:

“Send me the document that I left on your desk.” (Essential: which document?)

In a conversation:

“The restaurant, which just opened, serves amazing pizza.” (Extra: opening is extra)

In an order:

“I need the item that is on backorder.” (Essential: which item?)

Social situation:

“My friend, which I met in college, lives nearby.” (Incorrect – use “who”)
“My friend, whom I met in college, lives nearby.” (Correct)

Easy Trick to Remember

Try the “remove and check” trick. Read your sentence without the clause after that or which. If the sentence loses its main point or becomes unclear, use that. If the sentence still makes perfect sense, use which with commas.

For example:

• “The bike that has a red frame is mine.” (Remove “has a red frame” and the sentence becomes unclear.)
• “The bike, which has a red frame, is mine.” (Remove “has a red frame” and the bike is still mine.)

This simple trick works every time.

Mini Quiz

1. Which word introduces essential information?
   • a) which
   • b) that
2. Which word is usually set off with commas?
   • a) that
   • b) which
3. Is “The book, that I read, was good” correct?
   • a) Yes
   • b) No
4. Correct this sentence: “The house which I bought needs repairs.”
   • a) The house that I bought needs repairs.
   • b) The house, which I bought, needs repairs.
   • c) Both
5. Can “which” be used for people?
   • a) Yes
   • b) No
6. Remove the clause: “My bike, which I got for my birthday, is blue.” What is the main meaning?
   • a) My bike is blue.
   • b) I got the bike for my birthday.

Quiz Answers:

1. b
2. b
3. b
4. c (Both are correct depending on meaning)
5. b
6. a

Related Confusing Words

• who or whom
• affect or effect
• its or it’s
• your or you’re
• there or their
• then or than
• loose or lose
• accept or except

FAQs About That or Which

Is “that” or “which” always correct?
Both are correct in different situations. Use that for essential information and which for non-essential information.

What is the difference between “that” and “which”?
That introduces necessary, identifying information. Which introduces extra, non-essential information. Commas go before which but not before that.

Can I use “which” for essential clauses?
In formal writing, no. Use that for essential clauses. Some older style guides allow which, but modern practice prefers that.

Is “which” more formal than “that”?
No, both are equally formal when used correctly. Mistakes with which look unprofessional, but correct usage is always fine.

Do Americans and British writers use these differently?
No, both forms follow the same rule in American and British English.

Can I use “that” for people?
Yes, that can refer to people in informal contexts. For example, “The person that called me” is acceptable. However, who is more formal.

Conclusion

The rule for that and which is simple. Use that when the information is necessary to identify the noun. Use which with commas when the information is extra and can be removed. Remember the “remove and check” trick to test your sentence. With practice, choosing the right word will become automatic. Now you can write with confidence and clarity.

Sharpen Your English:

• Email or E-Mail | Which Spelling Looks Right When Your Words Need to Make a Good Impression?
• Counselling or Counseling | Why Both Spellings Exist and Which One Should You Choose?

Nolan Everhart

I am Nolan Everhart, a content writer interested in knowledge, useful discoveries, and practical guidance. I enjoy exploring questions that people commonly ask and breaking down information into straightforward explanations. My writing focuses on helping readers learn something valuable without having to search through confusing or unnecessary details. I believe that useful content should be accurate, engaging, and written with the reader’s needs in mind.

Books:

• The Everyday Knowledge Handbook
• Questions Worth Understanding