Deciding whether to place a comma before which vs that is one of the most common punctuation dilemmas writers face. Misplacing a comma does more than trigger a red squiggly line in your word processor; it can alter the factual meaning of your sentence.

Here is the quick rule to remember: use “that” without a comma for essential information, and use a comma before “which” for non-essential information.

This guide breaks down definitions, explores the difference between restrictive and non-restrictive clauses, explains regional differences between American and British English, and provides over 75 practical examples across daily, academic, and business communication.

+-------------------------------------------------------------------------+
|                              QUICK FORMULA                              |
|                                                                         |
|  [Noun] + that + [Essential details, NO commas]                         |
|  Example: The report that outlines our Q3 targets is ready.             |
|                                                                         |
|  [Noun], + which + [Bonus details, ALWAYS needs commas]                 |
|  Example: The report, which took four weeks to draft, is ready.         |
+-------------------------------------------------------------------------+

The Core Grammar Rule: Restrictive vs. Non-Restrictive Clauses

To master the choice between that and which, you must understand the distinction between restrictive (essential) and non-restrictive (non-essential) clauses.

1. Restrictive Clauses (Use That, No Comma)

A restrictive clause contains information vital to identifying the noun it modifies. If you remove this clause, the fundamental meaning of the sentence changes or becomes incomplete.

• Rule: Never place a comma before that when it introduces a restrictive clause.
• Example: The passport that expires next month must be renewed immediately.
  (Meaning: Only the specific passport expiring next month needs renewal, not your other passports.)

2. Non-Restrictive Clauses (Use Which, Needs a Comma)

A non-restrictive clause adds supplementary, parenthetical detail. The sentence remains factually complete and accurate if you remove it.

• Rule: Always place a comma before which when it introduces non-essential details. If the clause sits in the middle of a sentence, close it with a second comma.
• Example: My passport, which expires next month, is in the top drawer.
  (Meaning: The passport is in the top drawer. As a side note, it expires next month.)

When to Use a Comma Before Which vs That: The “Drop Test”

When editing your writing, apply the Drop Test to determine whether you need a comma before which or that:

Step 1: Read the sentence.
        "The laptop [which/that] has a cracked screen belongs to Marcus."

Step 2: Temporarily drop the bracketed clause.
        "The laptop belongs to Marcus."

Step 3: Ask: Does the listener still know WHICH specific laptop is being discussed?
        - If NO: The clause is essential. Use THAT without a comma.
          -> "The laptop that has a cracked screen belongs to Marcus."
        
        - If YES (e.g., Marcus only owns one laptop): The clause is bonus info. 
          Use A COMMA BEFORE WHICH.
          -> "Marcus's laptop, which has a cracked screen, is on the desk."

US English vs. UK English Differences

Style preferences vary across English-speaking regions:

• In American English: The distinction is strict. That never takes a comma; which always takes a comma when acting as a relative pronoun.
• In British, Australian, and Irish English: Writers sometimes write: “The car which I bought yesterday broke down.” While accepted in Commonwealth publishing, modern international style guides advise sticking to that for restrictive clauses to eliminate ambiguity.

Prepositional Phrases: When Which Does Not Take a Preceding Comma

A common point of confusion occurs when which follows a preposition, such as in which, for which, on which, or with which. In these cases, whether a comma appears before the preposition depends on whether the clause is restrictive or non-restrictive:

• Restrictive (No comma): The office in which I work has excellent heating.
• Non-restrictive (Comma before preposition): The downtown branch, in which we invested heavily, opened last week.

80 Practical Examples of “Which” vs. “That”

To build confidence, study these 80 original examples organized by category.

Category 1: Everyday Life and Daily Conversations (Examples 1–10)

1. That: The keys that unlock the garage are hanging by the front door.
2. , which: My house keys, which I dropped in the driveway, were scratched.
3. That: A dog that barks constantly can frustrate neighbors.
4. , which: Our family rescue dog, which is a beagle mix, loves sleeping on the rug.
5. That: Please return the bicycle that has the flat rear tire.
6. , which: My sister’s bicycle, which she purchased second-hand, runs smoothly.
7. That: The grocery store that stays open twenty-four hours is down the street.
8. , which: The corner market, which closed last year, is now an artisan bakery.
9. That: Shoes that pinch your toes will cause blisters during a long walk.
10. , which: My hiking boots, which cost over two hundred dollars, lasted ten seasons.

Category 2: Business and Workplace Communication (Examples 11–20)

11. That: All employees must complete the training module that covers workplace compliance.
12. , which: The annual safety seminar, which takes place every September, is mandatory.
13. That: Contracts that lack an explicit termination clause present legal risks.
14. , which: The vendor contract, which was drafted by external counsel, is ready for signature.
15. That: We need a software program that automatically synchronizes inventory numbers.
16. , which: Enterprise Resource Planning tools, which require extensive training, reduce human error over time.
17. That: The candidate that demonstrates strong communication skills will advance to round two.
18. , which: Sarah Jenkins, which is a name you might remember from the conference, applied for the director post. (Note: For people, use “who”, but when referencing entities:) Our parent firm, which acquired two competitors this quarter, reported steady growth.
19. That: The department that generates the highest sales volume receives quarterly bonuses.
20. , which: The marketing department, which recently restructured its leadership, launched the campaign.

Category 3: Academic and Research Writing (Examples 21–30)

21. That: Hypotheses that cannot be tested through empirical research should be discarded.
22. , which: The original working hypothesis, which was formulated in 2021, proved inaccurate.
23. That: Data sets that contain missing variables must undergo statistical normalization.
24. , which: The primary survey dataset, which includes 3,000 respondents, is publicly accessible.
25. That: Scholars that study macroeconomic volatility focus on interest rates. (Better with things:) Books that examine macroeconomic policy line our library shelves.
26. , which: John Maynard Keynes’s seminal treatise, which revolutionized macroeconomics, remains influential.
27. That: The laboratory instruments that require recalibration are labeled in red.
28. , which: The electron microscope, which was manufactured in Germany, provides atomic resolution.
29. That: Experiments that fail to replicate in peer review undermine scientific validity.
30. , which: The longitudinal study, which ran for over three decades, produced valuable insights into cognitive decline.

Category 4: Professional Email Writing (Examples 31–40)

31. That: Please send over the revised slide deck that we discussed during this morning’s call.
32. , which: I have attached the latest invoice, which reflects our agreed-upon discount.
33. That: The meeting that was originally planned for Thursday has moved to Friday afternoon.
34. , which: Tomorrow’s standup meeting, which should only take ten minutes, starts at 9:00 AM.
35. That: Any email that arrives after business hours will receive an automated response.
36. , which: Our customer support inbox, which receives hundreds of inquiries daily, is monitored continuously.
37. That: Let us review the action items that pertain to the international rollout.
38. , which: The project timeline, which the client approved on Monday, leaves no room for delays.
39. That: I left the project brief that needs your signature on your desk.
40. , which: The revised project proposal, which incorporates stakeholder feedback, is attached below.

Category 5: Student and ESL Essentials (Examples 41–50)

41. That: The textbook that I bought for biology class is missing chapter three.
42. , which: My English textbook, which has 400 pages, is heavy to carry.
43. That: The bus that stops in front of the high school leaves every fifteen minutes.
44. , which: Bus 42, which connects the campus to downtown, is delayed today.
45. That: Homework that is turned in late will lose ten percentage points.
46. , which: The final research essay, which counts for 30% of our course grade, is due next Friday.
47. That: The desk that sits near the radiator gets uncomfortably warm.
48. , which: Room 204, which houses our chemistry lab, was renovated over the break.
49. That: Pens that run out of ink during an exam can cause unnecessary stress.
50. , which: My favorite fountain pen, which was a graduation gift from my grandfather, writes smoothly.

Category 6: Prepositional & Advanced Structural Usage (Examples 51–60)

51. In that vs. In which (Restrictive): The exact room in which the peace treaty was signed is preserved as a museum.
52. Non-restrictive with preposition: The treaty room, in which tourists are not allowed to take photographs, was renovated last year.
53. For which (Restrictive): The reason for which the CEO resigned remains undisclosed to the press.
54. For which (Non-restrictive): His philanthropic foundation, for which he was knighted, supports underprivileged youth.
55. Of which (Non-restrictive): The company owns fifteen commercial aircraft, ten of which are leased to international carriers.
56. At which (Restrictive): The temperature at which this chemical compound vaporizes is roughly 150 degrees Celsius.
57. At which (Non-restrictive): The historic summit, at which world leaders signed the climate accord, concluded yesterday.
58. Clauses modifying entire sentences: The flight was delayed three hours, which caused us to miss our connecting train in Paris.
59. Sentential modifier: He decided to decline the lucrative job offer, which surprised his colleagues and mentors.
60. Double clause test: The policy that prohibits personal phone calls, which was enacted last May, faces heavy staff resistance.

Category 7: Paired Contrasts (How One Comma Changes the Meaning) (Examples 61–70)

The presence or absence of a comma fundamentally changes what you are telling your reader.

61. Sentence A (Restrictive – No Comma):
    The vegetables that were grown organically sold out within an hour.
    (Meaning: Only the organic vegetables sold out; the conventional vegetables remained on the shelf.)
62. Sentence B (Non-Restrictive – With Comma):
    The vegetables, which were grown organically, sold out within an hour.
    (Meaning: All the vegetables sold out; as an aside, all of them were grown organically.)
63. Sentence A:
    The houses that have swimming pools require higher insurance premiums.
    (Meaning: Only houses with pools have higher premiums.)
64. Sentence B:
    The houses, which have swimming pools, require higher insurance premiums.
    (Meaning: All the houses in this discussion have pools and higher premiums.)
65. Sentence A:
    The restaurants that failed health inspections were forced to close immediately.
    (Meaning: Only the failing restaurants closed.)
66. Sentence B:
    The restaurants, which failed health inspections, were forced to close immediately.
    (Meaning: All restaurants in the group failed their inspections and were closed.)
67. Sentence A:
    The software updates that contain security patches must be installed today.
    (Meaning: Install only the updates addressing security.)
68. Sentence B:
    The software updates, which contain security patches, must be installed today.
    (Meaning: Install all the updates; by the way, they happen to contain security patches.)
69. Sentence A:
    The employees that met their sales quotas received a holiday bonus.
    (Meaning: Only staff members who hit their numbers received bonuses.)
70. Sentence B (Incorrect referent for humans, but for business units):
    The branches, which met their sales quotas, received celebratory plaques.
    (Meaning: All branches reached their target and received plaques.)

Category 8: Common Mistakes Fixed (Examples 71–80)

3 Easy Rules of Thumb to Remember

1. That = Crucial / No Comma:
   If the sentence loses its intended meaning when the clause disappears, write that with no comma.
2. Which = Bonus / Use a Comma:
   If the clause feels like it belongs in parentheses (like this), write a comma before which.
3. Never Put a Comma Before “That”:
   In standard English relative clauses, never put a comma before that. Seeing , that is almost always a sign of a punctuation error.

Practice Exercises

Rewrite each sentence by selecting either that (no comma) or , which (with comma). Answers are below.

1. The coffee shop [that / , which] opened on Elm Street serves fair-trade espresso. (Assume there are many coffee shops in town.)
2. My wedding ring [that / , which] is made of platinum was designed by a local jeweler. (Assume the speaker has only one wedding ring.)
3. The train [that / , which] stops at every station takes an hour longer to reach the terminal.
4. The Empire State Building [that / , which] was completed in 1931 remains an architectural icon.
5. All students must bring the textbook [that / , which] corresponds with their syllabus.

Answer Key with Explanations

1. Answer: that
   The coffee shop that opened on Elm Street serves fair-trade espresso.
   Explanation: “That opened on Elm Street” is restrictive; it tells us which specific coffee shop serves fair-trade espresso.
2. Answer: , which
   My wedding ring, which is made of platinum, was designed by a local jeweler.
   Explanation: The speaker has only one wedding ring, making its platinum composition non-essential descriptive detail.
3. Answer: that
   The train that stops at every station takes an hour longer to reach the terminal.
   Explanation: Essential clause. It specifies the slow local train rather than the express train.
4. Answer: , which
   The Empire State Building, which was completed in 1931, remains an architectural icon.
   Explanation: The subject is a proper noun and a unique entity. The construction year is non-essential parenthetical information.
5. Answer: that
   All students must bring the textbook that corresponds with their syllabus.
   Explanation: Essential. Students do not need to bring just any textbook; they need the specific one matched to their syllabus.

Interactive 5-Question Quiz

Test your mastery of the comma before which vs that:

Q1: Which sentence uses correct American English punctuation?
A) The assignment, that is due on Monday, is difficult.
B) The assignment that is due on Monday is difficult.
C) The assignment which is due on Monday is difficult.
D) The assignment, that is due on Monday is difficult.

Q2: True or False: In a relative clause, you should never place a comma directly before “that.”
A) True
B) False

Q3: Which sentence implies that the speaker owns MORE THAN ONE car?
A) My car, which has a broken air conditioner, is at the mechanic.
B) My car that has a broken air conditioner is at the mechanic.

Q4: Fill in the blank: “The Mona Lisa _______ hangs in the Louvre, was painted by Leonardo da Vinci.”
A) that
B) , that
C) , which
D) which

Q5: Which sentence correctly introduces a non-restrictive clause in the middle of a sentence?
A) Our corporate headquarters, which was built in 1995 needs major roof repairs.
B) Our corporate headquarters which was built in 1995, needs major roof repairs.
C) Our corporate headquarters, which was built in 1995, needs major roof repairs.
D) Our corporate headquarters that was built in 1995, needs major roof repairs.

Quiz Answers & Scoring Guide

• Q1: B — Restrictive clauses require that without commas. Option A incorrectly places commas around that, and Option C neglects the US preference for that in essential clauses.
• Q2: A (True) — In relative clauses, a comma never belongs immediately before the restrictive pronoun that.
• Q3: B — “That has a broken air conditioner” is restrictive, indicating that out of multiple cars owned, this specific one is in the shop. In Option A, the commas indicate the speaker has only one car.
• Q4: C — Because the Mona Lisa is unique, any descriptive detail is non-restrictive and requires a pair of commas: , which.
• Q5: C — Non-restrictive clauses occurring mid-sentence must be bounded by a comma before which and a closing comma at the end of the clause.

Frequently Asked Questions (FAQ)

Can you ever put a comma before “that”?

In relative clauses, no. You should never place a comma before that when it introduces essential information about a noun. The only time a comma appears before that is when that introduces an independent clause after a parenthetical interrupter or when writing direct dialogue (e.g., “He said, ‘Look at that.'”).

Why do British writers use “which” without commas?

British English treats which more flexibly than American English. Commonwealth style guides allow which to head restrictive clauses without a comma (“The car which won the race was blue”). However, to prevent ambiguity across global audiences, international publications recommend using that for restrictive clauses.

How do I know if an item is restrictive or non-restrictive?

Use the Drop Test. Read your sentence without the descriptive clause. If the sentence loses its primary identifying information, it is restrictive (use that, no comma). If the basic message remains intact, it is non-restrictive (use a comma before which).

Does this rule apply to people?

No. When referring to people, use who or whom rather than that or which.

• Restrictive: The doctor who performed the surgery is well-known.
• Non-restrictive: Dr. Smith, who performed the surgery, is well-known.

What happens if “which” appears at the end of a sentence?

If a non-restrictive clause introduced by which appears at the end of a sentence, place a comma before which and end the clause with a period:

• She decided to buy the red bicycle, which was significantly cheaper.

Conclusion & Summary Checklist

Knowing whether to place a comma before which vs that ensures your writing is clear and grammatically sound.

• Use “that” when the details are critical to understanding which item is being discussed. Do not add a comma.
• Use “, which” when offering parenthetical, non-essential commentary that could be deleted without changing the factual core of the sentence.
• Double commas for mid-sentence clauses: When using a non-restrictive which clause inside a sentence, remember to close it with a comma before continuing your thought.

Editorial Disclaimer

This article reflects standard international English grammar guidelines, including the Chicago Manual of Style, APA 7th Edition, and Oxford A-Z of Grammar and Punctuation. Regional variations between US and Commonwealth practices are noted to provide context for academic, professional, and cross-border publishing.

Also Read: A Lot of People Is or Are? The Correct Grammar Rule

Each of the Students Is or Are? The Complete Subject-Verb Agreement Guide

admin