Mastering English grammar requires a clear understanding of small words that carry significant meaning. Two terms that frequently confuse writers, students, and English language learners are “their” and “theirs.” While both words express ownership or possession related to a group of people or things, they function differently inside a sentence.

If you have ever stopped mid-sentence wondering whether to write “is that car their car?” or “is that car theirs?”, this guide will clarify the rules once and for all.

In this comprehensive lesson, we will break down the precise their vs theirs difference with examples, explore how each word works grammatically, provide over 75 practical examples across multiple settings, and offer practice exercises to test your skills.

Quick Reference: The Core Rule

Before diving into detailed explanations, here is the golden rule to remember:

• “Their” is a possessive adjective (also called a possessive determiner). It must always be followed by a noun (their car, their ideas, their project).
• “Theirs” is a possessive pronoun. It stands alone and replaces both the possessive word and the noun (the car is theirs, the ideas are theirs, the project is theirs).

Comparison at a Glance

Step-by-Step Explanation of Their vs. Theirs

To understand the their vs theirs difference with examples, let’s look at how each word operates step by step.

       [ POSSESSION: BELONGS TO THEM ]
                     │
         ┌───────────┴───────────┐
         ▼                       ▼
    Needs Noun?            No Noun Next?
         │                       │
         ▼                       ▼
      THEIR                   THEIRS
 (Possessive Adjective)   (Possessive Pronoun)
 Example: "their books"   Example: "the books are theirs"

Step 1: Understanding “Their” (Possessive Adjective)

The word their shows that something belongs to two or more people, animals, or objects (or a single person when using the singular “they”). Because it acts as an adjective, it modifies a noun. That means their cannot stand alone; it must sit directly in front of the noun it describes.

• Correct: Where is their room? (The word “room” is the noun).
• Incorrect: Where is their? (Incomplete sentence; missing the noun).

Step 2: Understanding “Theirs” (Possessive Pronoun)

The word theirs is a pronoun. Pronouns exist to replace nouns or noun phrases so we don’t repeat ourselves. Because theirs contains the meaning of both “their” and the item being owned, it never takes a noun after it.

• Correct: That room is theirs. (Stands alone; replaces “their room”).
• Incorrect: That is theirs room. (Redundant and grammatically incorrect).

Comprehensive Example Bank (75+ Original Examples)

To build strong intuition, let’s look at real-world scenarios organized by category.

Category 1: Basic Examples (Simple Sentences)

1. Their dogs bark every morning.
2. Those barking dogs are theirs.
3. I found their keys on the kitchen table.
4. I found a set of keys; I think they are theirs.
5. Their garden looks beautiful this spring.
6. The house with the beautiful garden is theirs.
7. We watched their team win the championship.
8. The victory trophy is finally theirs.
9. Please return their coats at the door.
10. Are those warm coats theirs?

Category 2: Intermediate Examples (Complex Sentences & Comparisons)

11. While our team finished the report early, their team requested an extension.
12. Our proposal was submitted yesterday, but theirs came in this morning.
13. Although their luggage was lost at the airport, our baggage arrived safely.
14. If you cannot find your passports, we can store theirs in the hotel safe.
15. Her strategy focuses on digital marketing, whereas their strategy relies on print media.
16. Our design won second place, but the judge declared that the ultimate decision was theirs.
17. I enjoyed their performance, though I thought the opening act was better.
18. Your seats are in row five, and theirs are right behind yours in row six.
19. We respect their decision to relocate the headquarters.
20. The final choice was entirely theirs, and we must honor it.

Category 3: Advanced & Nuanced Examples (Formal & Literary Constructs)

21. The committee members submitted their individual reports prior to the annual review.
22. Among all the research grants awarded this year, the highest allocation was theirs.
23. Every country must protect their natural resources for future generations.
24. The responsibility for maintaining the shared courtyard is ultimately theirs.
25. Scholars often defend their published hypotheses against severe academic criticism.
26. While several architectural firms entered the competition, the winning design was theirs.
27. Delegates expressed their commitment to reducing international emissions.
28. The land had belonged to the indigenous community for centuries; the heritage was rightfully theirs.
29. The analysts published their quarterly projections yesterday afternoon.
30. Our firm’s projections were conservative, but theirs proved remarkably accurate.

Category 4: Daily Conversation Examples

31. “Did you see their new car?”
32. “Yes, that red sedan parked outside is theirs.”
33. “Are these their shoes by the entrance?”
34. “No, those aren’t theirs; those belong to Sam.”
35. “I love their sense of humor.”
36. “Is that broad smile theirs or yours?”
37. “We should ask for their opinion before booking.”
38. “The decision is theirs, so let’s wait for their call.”
39. “Can you hand me their coats?”
40. “Don’t worry about the umbrellas; theirs are already in the trunk.”

Category 5: Academic Writing Examples

41. The researchers conducted their experiment under strictly controlled conditions.
42. Data collected in group A was invalidated, but the data from group B was clearly theirs.
43. Authors must disclose any potential conflicts of interest in their manuscripts.
44. The prevailing theory was challenged when new evidence contradicted theirs.
45. Students must cite their sources accurately to avoid plagiarism.
46. While several scholars claimed the discovery, primary documentation proved it was theirs.
47. The participants gave their informed consent before the study began.
48. The control group retained their notes, while the experimental group submitted theirs.
49. The faculty members expanded their curriculum to include environmental ethics.
50. The intellectual property generated during the lab study remains theirs.

Category 6: Business & Professional Writing Examples

51. The board members cast their votes regarding the upcoming merger.
52. Our company increased market share by 5%, while theirs decreased by 2%.
53. Executives outlined their vision for the fiscal year during the keynote.
54. The competing firm lowered prices, but our quality remains superior to theirs.
55. Shareholders expressed their concerns during the annual general meeting.
56. Both agencies presented campaigns, but the client preferred theirs.
57. Employees are encouraged to upload their compliance certificates.
58. The copyright to the software platform is legally theirs.
59. The sales representatives updated their client profiles in the CRM system.
60. Our legal department reviewed the contract terms alongside theirs.

Category 7: Workplace & Email Examples

61. Email: “Please remind the contractors to send their updated invoices by Friday.”
62. Email: “We have finalized our budget draft; has the accounting team submitted theirs?”
63. Email: “Thank you for sharing your slides. We look forward to seeing their presentation.”
64. Email: “If the marketing team misplaced the media kit, they can borrow theirs from the folder.”
65. Email: “The client accepted our timeline, but we are still waiting for their feedback.”
66. Workplace: “Someone left their badge on the conference room table.”
67. Workplace: “If you find a blue notebook, please return it—it is theirs.”
68. Workplace: “The IT department updated their security protocols today.”
69. Workplace: “Our department completed the training modules, but theirs is scheduled for next week.”
70. Workplace: “Please ensure all attendees sign their non-disclosure agreements.”

Category 8: Student & ESL Learner Examples

71. Their teacher explained the lesson clearly.
72. That colorful backpack is theirs.
73. Children like playing with their toys.
74. The toys on the floor are theirs.
75. Where did they park their bicycles?
76. Those bicycles are theirs.
77. They forgot their homework today.
78. Is this lunchbox theirs?
79. Their family moved to a new city.
80. The choice to join the club was theirs.

Direct Comparison: Correct vs. Incorrect Table

Understanding common errors helps solidify the rule. Study these contrasts carefully:

Common Pitfalls: “Their’s” vs. “There’s” vs. “They’re”

Confusion often extends beyond just their and theirs. Writers frequently mix up homophones and apostrophe placements.

               [ HOMOPHONE & SPELLING GUIDE ]
  _______________________________________________________
 | Word     | Category          | Meaning / Function     |
 |----------|-------------------|------------------------|
 | their    | Possessive Adj.   | Belonging to them      |
 | theirs   | Possessive Pronoun| Belonging to them      |
 | they're  | Contraction       | Short for "they are"   |
 | there    | Adverb / Expletive| A place or point       |
 | there's  | Contraction       | Short for "there is"   |
 | their's  | INVALID WORD      | DOES NOT EXIST!        |
 |____________|___________________|________________________|

1. The “Their’s” Trap (The Non-Existent Word)

The word their’s does not exist in the English language.

• Incorrect: The decision was their’s.
• Correct: The decision was theirs.

Why? Possessive pronouns in English—such as yours, hers, ours, its, theirs—already express possession intrinsically. Adding an apostrophe is grammatically invalid.

2. Confusing “Theirs” with “They’re”

• They’re is a contraction for “they are.”
• Theirs shows ownership.
• Incorrect: They’re car is parked over there.
• Correct: Their car is parked over there.
• Incorrect: The victory is they’re.
• Correct: The victory is theirs.

3. Confusing “Theirs” with “There’s”

• There’s is a contraction for “there is” or “there has.”
• Theirs shows ownership.
• Incorrect: Is that hat there’s?
• Correct: Is that hat theirs?
• Correct: There’s a hat on the chair.

Easy Memory Hacks to Remember the Rule

1. The Noun Test:
   • Look at the word immediately after.
   • Noun present? Use THEIR (their house).
   • No noun present? Use THEIRS (the house is theirs).
2. The Letter “S” Trick:
   • The “S” in theirs stands for “Solitary” or “Stands Alone.” When the word stands alone at the end of a clause without a noun, use the one with the S!
3. The Apostrophe Prohibition:
   • Repeat this mantra: “No apostrophe in possessive pronouns!” Just like his and hers do not have apostrophes, theirs never takes one.

Practice Exercises

Test your understanding by filling in the blanks with either their or theirs.

Exercise Questions

1. The students submitted ___________ assignments before the deadline.
2. We brought our sleeping bags, but they forgot ___________.
3. Is that blue sailboat ___________?
4. The birds built ___________ nest high in the oak tree.
5. Our company expanded its market, and ___________ expanded as well.
6. Please make sure that all visitors sign ___________ names at the front desk.
7. I found a pair of glasses; do you know if they are ___________?
8. ___________ flight was delayed by two hours due to bad weather.
9. That land was once ___________, but it was sold years ago.
10. The children finished ___________ dinner early tonight.

Answer Key with Explanations

1. their — Followed by the noun “assignments”.
2. theirs — Stands alone at the end of the clause; replaces “their sleeping bags”.
3. theirs — Stands alone as a predicate pronoun; no noun follows it.
4. their — Followed by the noun “nest”.
5. theirs — Stands alone as the subject of the clause; replaces “their company”.
6. their — Followed by the noun phrase “names”.
7. theirs — Stands alone; replaces “their glasses”.
8. Their — Followed by the noun “flight”.
9. theirs — Stands alone after the linking verb “was”.
10. their — Followed by the noun “dinner”.

5-Question Quiz

Test your knowledge with these quick multiple-choice questions.

Question 1

Which of the following sentences is grammatically correct?
A) The fault for the error was completely their’s.
B) The fault for the error was completely their.
C) The fault for the error was completely theirs.
D) The fault for the error was completely there’s.

Question 2

Choose the word that correctly fills the blank: “All passengers must keep ___________ personal belongings with them at all times.”
A) theirs
B) their
C) their’s
D) they’re

Question 3

Identify the sentence that uses a possessive pronoun correctly:
A) Our dog is friendly, but theirs dog is aggressive.
B) Our dog is friendly, but theirs is aggressive.
C) Our dog is friendly, but their’s is aggressive.
D) Our dog is friendly, but there’s is aggressive.

Question 4

Why is the word “their’s” incorrect in standard English writing?
A) Because it requires a hyphen instead of an apostrophe.
B) Because possessive pronouns do not use apostrophes to show ownership.
C) Because it is only used in formal British English.
D) Because it can only be placed at the beginning of a sentence.

Question 5

Complete the sentence pair: “That is ___________ business model. The choice to change it is ___________.”
A) theirs / their
B) their / theirs
C) their’s / theirs
D) their / their’s

Quiz Answer Key & Explanations

1. C — Theirs is the correct possessive pronoun. Options A and D misuse apostrophes, while Option B lacks the required pronoun form.
2. B — Their is correct because it directly modifies the noun phrase “personal belongings”.
3. B — Theirs correctly stands alone without modifying a noun. Option A incorrectly places a noun after theirs.
4. B — Possessive pronouns (yours, hers, his, ours, theirs) never take apostrophes.
5. B — The first blank modifies the noun “business model” (their), while the second blank stands alone at the end of the sentence (theirs).

Frequently Asked Questions (FAQs)

1. What is the fundamental difference between “their” and “theirs”?

Their is a possessive adjective that must sit right before a noun (their house). Theirs is a possessive pronoun that replaces the noun phrase altogether and stands on its own (the house is theirs).

2. Can you ever write “their’s” with an apostrophe?

No, never. In standard English, “their’s” is always grammatically incorrect. Possessive pronouns like theirs, ours, yours, and hers do not take apostrophes.

3. Can “theirs” be used at the beginning of a sentence?

Yes. “Theirs” can act as the subject of a sentence. For example: “Our presentation went well, but theirs was extraordinary.” Here, theirs stands in for “their presentation.”

4. Is “their” singular or plural?

Historically, “their” was strictly plural (referring to two or more people). However, in modern standard English (including AP, Chicago, and Oxford styles), “their” is also widely accepted as a singular, gender-neutral pronoun (“Every employee should bring their laptop”).

5. How do I choose between “their,” “there,” and “they’re”?

• Use their to show possession before a noun (their car).
• Use there to point to a place or state of being (over there, there is).
• Use they’re as a contraction for “they are” (they’re running late).

Conclusion

Understanding the their vs theirs difference with examples comes down to recognizing sentence structures:

• Use their when a noun immediately follows to describe ownership (their + noun).
• Use theirs when the word stands alone, replacing the noun entirely.
• Never use an apostrophe with theirs.

By keeping these rules in mind and reviewing the categorized examples above, you can confidently write clear, accurate, and professional English.

Have a grammar question? Drop your practice sentences in the comments below, and our editors will review them for you! Don’t forget to bookmark this guide or share it with a colleague who wants to polish their professional writing.

Disclaimer

This article is provided for educational and informational purposes. While every effort is made to align with standard international style guides (including AP, Chicago, and Oxford), specific editorial preferences may vary across individual institutions, publishers, or corporate style manuals.

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