30 Common Grammar Mistakes You Need To Stop Making

Are you afraid of making common grammar mistakes? Consider: “Let’s eat kids!” Sounds terrifying, right? 

Use the commonplace comma at the right juncture and voila, your meaning is clear! A horrifying act is transformed into a pleasurable activity.  

In the above example, the correct sentence would read, “Let’s eat, kids!”

The most common grammar mistakes in the English language are incorrect punctuation and spelling. 

To help you out, I’ve included the 30 most common grammatical errors that I used to make before seeing the light of syntax in this article. Reference these when editing your next piece.

I’ve mentioned a few online grammar checkers you could use to find grammar mistakes and create error-free prose. Let’s get started.

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30 Most Common Grammar Mistakes In English

To help you write grammatically correct and complete sentences, here’s a list of 30 grammar mistakes most writers make:

Words and Phrases

1. “It’s” vs. “Its”

Usually, an apostrophe indicates possessive nouns, as in “the dog’s bone” or “children’s books.”

However, in this case, the opposite is accurate:

It’s, which has an apostrophe, is a contraction of it is or it has.

Its, which doesn’t have an apostrophe, is a possessive pronoun that’s used to show something belongs to someone/something else. 


It’s (it is) raining in London.

The dog ate from its bowl.

2. “You’re” vs. “Your”

You’re is the contraction of you are.

Your is the possessive form that indicates something or someone is associated with a person other than yourself.


You’re riding in the front seat.

What’s your favorite color?

3. “That” vs. “Who”

Use that when referring to things, groups, people, animals or objects.

Use who/m only when referring to people.


Amy is on the team that won first place.

Who is in charge?

The guy whom you said is brilliant recently joined the company.

4. “Which” vs. “That”

Which is used to describe.

That is used to define. 

To avoid confusion, determine if the phrase that follows which/that is essential to its meaning. If it’s a vital phrase, use that. Otherwise, use which.


John built that house.

This house, which John built, resembles his house.

5. “May” vs. “Might”

May is used to express something possible or factual.

Might is used to express something hypothetical. It indicates you are less likely to do something. Might is also the past tense of may.


He may lose his job.

If I win the lottery, I might buy a Ferrari.

May and Might are also used when asking for permission.


May I borrow your pen?

Might I ask for a favor?

6. “I” vs. “Me”

I” is a subject pronoun, which means it’s used as a subject in a sentence.

Me” is an object pronoun, meaning it’s used as an object to a verb.


I went to the museum yesterday.

My mom scolded me for being late.

In the second example, “me” is the object of “scolded”. The object of the preposition “foris being late.

7. “Let’s” vs. “Lets”

Let’s is short for let us.

Lets is the present tense form of the verb let, which means allows.


Let’s go out this evening.

She lets her children play outside.

8. “Lay” vs. “Lie”

Lay means to place something in a flat position. It requires an object.

Lie means to rest in a flat position. It doesn’t require an object.


Please lay the book on the table.

My dog likes to lie on the bed.

Here’s a table to help you use lay and lie correctly: 

Present TenseLayLie
Past TenseLaidLay
Past ParticipleLaid Lain
Present ParticipleLayingLying

9. “Affect” vs. “Effect”

Affect (verb) means to impact.

Effect (noun) is the result of that impact. 


The bushfires affected the people of Sydney.

The effect of the bushfires was devastating.    

However, sometimes, affect is used as a noun and effect is used as a verb. In such cases:

Affect (noun) means feeling.

Effect (verb) means to bring about a change.


The doctor observed the patient’s affect  

The people wanted to effect a change in the government’s policies.

10. “Irregardless”

“Irregardless” is a redundant word that has the same meaning as regardless — having no regard or concern for someone/something. 

While there’s nothing wrong with using this word, it’s best to avoid redundant words in your writing as it can look wordy. 

11. “Literally”

While “literally” means “exactly, without exaggeration”, people often use it to exaggerate situations. 


When I saw Queen Elizabeth, I literally died. 

If the person had literally died, they wouldn’t be saying this in the first place!

While using literally to exaggerate is quite common, avoid using the word in formal writing. 


I could figuratively eat an entire cow right now.

12. “First come, first serve”

It should be “first come, first served.” 

Without the d, the phrase implies that the person who comes first will be serving the others — the opposite of what it actually means. 


The seats were allotted on a first-come, first-served basis.

13. “Peace of mind” vs. “Piece of mind”

Peace of mind is a mental state of tranquility.

Piece of mind incorrectly states “a piece of my mind”, which is used to express a strong opinion or anger.


His mum had no peace of mind until he returned from his tour.

I’m going to give that mechanic a piece of my mind if the car is still not fixed this time.


Many common grammar mistakes involve homophones.

I have listed some homophones that may invade your writing. Keep a lookout for these words that sound the same but have different meanings! 

14. “There” vs. “Their” vs. “They’re”

There refers to a place.

Their refers to something owned by a group.

They’re is a contraction of they are.


Your pink pajamas are over there. 

The poodle is their dog. 

I guess they’re not as tame as they look.

15. “Lose” vs. “Loose”

Lose means to be deprived of something.

Loose means not fixed in place.


He didn’t want to lose his cattle to the wolves.

Your belt is loose.

16. “Into” vs. “In to”

Into expresses the movement of something towards something else.

In to is short for in order to.   


Mary moved into the apartment last weekend.

She dropped in to say hello.

17. “Compliment” vs. “Complement”

Compliment means to praise or congratulate someone.

Complement means something that improves something else or makes it complete.


The fact that she likes my painting is a major compliment.

Their personalities complement each other.

18. “Peek” vs. “Peak” vs. “Pique”

Peek means to look quickly at something.

Peak refers to a sharp point.

Pique is a feeling of arousal or annoyance.


Please open the door and peek inside.

Jane reached the peak of the mountain.

The movie piqued the audience’s interest.

19. “Emigrate” vs. “Immigrate”

Emigrate means to leave one’s country.

Immigrate means arriving in another country to live there. 

Here’s a mnemonic to help you remember the difference:

Emigrate is to immigrate as go is to come.


He dropped his plans to emigrate from his country. 

She wants to immigrate to Canada to lead a better life.

20. “Principal” vs. “Principle”

Principal refers to someone or something important.

Principle implies a concept, philosophy or fundamental truth.


London is a principal city in the UK.

Putting the customer’s interest first is a good business principle.

21. “Farther” vs. “Further”

Farther refers to a measurable distance.

Further describes a quantity, time or metaphorical distance.


Mexico is farther from Canada than the United States.  

The officer offered no further information about the case.

Grammatical Structures

22. Using Commas

Commas are always pesky — they’re essential, but have more rules and applications. 

That’s why they’re often referred to as the hardest punctuation in English grammar.

With a little care, you can use them properly. Here are some basic rules for using commas:

1. Use commas to separate items in a series.


I like to eat cakes, ice creams, and puddings. 

That last comma is known as an Oxford comma. It’s optional and depends on the writing style guide you’re following. 

2. Use a comma for coordinate adjectives.

When two adjectives modify the same noun in the same way, you need to put a comma between them. If you can replace the comma with the word and, then the adjectives are coordinate adjectives.


It is going to be a long, hot summer.

3. If a dependent clause starts a sentence, use a comma after it.


When I went to the park, I saw a peacock.

4. Use commas to offset non-essential information in a sentence.


Kate, who is my friend, topped the exam.

5. Use a comma after certain introductory phrases in a sentence.


Grabbing her umbrella, Kate raced out of the house. 

However, she can be short-tempered.

6. Use a comma before a coordinating conjunction (and, but, for, nor, or, so, yet) that connects two or more independent clauses.

An independent clause is a sentence that can stand on its own. Commas can connect two or more independent clauses only if a coordinating conjunction links them.


I went to the store, but I forgot to bring the grocery list.

Today is a study day, and the exam is Wednesday. 

Special Case: Run-on Sentence and Comma Splice

A run-on sentence is a sentence that’s formed from independent clauses without using any coordinating conjunctions or punctuation. Writing becomes complicated and confusing in such sentences.

Example: She loves gardening she’s great with flowering plants.

A comma splice is a form of run-on sentence where two or more independent clauses are connected using only a comma and no coordinating conjunction. 

Example: She loves gardening, she’s great with flowering plants.

While using a comma to connect the clauses, the idea is still unclear to the reader. Instead of a comma splice, you could use:

A comma and a coordinating conjunction
Example: She loves gardening, and she’s great with flowering plants.

A period
Example: She loves gardening. She’s great with flowering plants.

A semicolon
Example: She loves gardening; she’s great with flowering plants.

A subordinating conjunction
Example: She loves gardening as she’s great with flowering plants.

23. Using Semicolons

Semicolons link two independent clauses without using a conjunction like and

Example: Some people write using Microsoft Word; others prefer to use Google Docs.

Here are some basic rules for using semicolons:

1. Use semicolons to separate items in a list when those items contain commas (long comma lists).

Example: I want to travel to London, England; Berlin, Germany; Rome, Italy; and Tokyo, Japan. 

2. Delete the conjunction when using a semicolon

It would be redundant to use both a semicolon and a conjunction together in a sentence.

I went to the dog park; my friend met me there.

Correct: I went to the dog park; my friend met me there.

3. Use semicolons with transitional words (conjunctive adverbs)

Some common conjunctive adverbs include moreover, nevertheless, however, otherwise, therefore, then, “finally“, “likewise”, “in addition and consequently

Example: Reports of the hurricane’s damage were greatly exaggerated; indeed, the storm was not a “hurricane” at all.

24. Quotation Marks and Punctuation

While quotation marks can breathe life to your writing, many people get confused about punctuating them.

Here’s how to use punctuation with quotation marks:

1. Colons, semicolons, and dashes are placed outside quotation marks

Example: Peter was aware of what he called “Paul’s weakness triangle”: he was half deaf, slept like a log, and was prone to lying.

2. Commas and periods always go inside quotation marks in American English

Example: I often misspell “successful.” (American English)

However, according to the Guardian Style Guide which reflects the British style: Place full points and commas inside the quotes for a complete quoted sentence; otherwise the point comes outside. 

Example: “Anna said: ‘Your style guide needs updating,’ and I said: ‘I agree.’”
(but) “Anna said updating the guide was ‘a difficult and time-consuming task’.” 

3. If question marks and exclamation points are part of the quotation, they go inside; otherwise, they go outside the quotation marks

Example: She asked me, “Can we have roast turkey for dinner?”

Example: Did she actually say, “His roasted turkey tasted unseasoned”?

25. Subject-Verb Agreement

Most common grammar mistakes happen when the subject or verb disagrees with the other in number. Subjects and verbs must always agree in number. Both need to be in the singular or plural form. 

Here are some subject-verb agreement rules:

1. If the subject is singular, use a singular verb

Example: She talks a lot.

2. If the subject is plural, use a plural verb 

Example: They talk a lot.

3. When the subject has two or more nouns or pronouns joined by and, use a plural verb

Example: John and Joy are going skiing.

4. When two or more singular nouns or pronouns are joined by or/nor, use a singular verb

Example: The chairperson or the CEO approves the proposal before proceeding.

5. When a compound subject has both a singular and a plural noun or pronoun joined by orornor, the verb should agree with the noun or pronoun that’s closest to it


The principal or the teachers conduct the quiz.

The teachers or the principal conducts the quiz.

6. With collective nouns like everybody, everyone, somebody, anybody, etc., use a singular verb

Example: Everyone wants to participate in the quiz.

26. Pronoun Agreement

While a subject and verb must agree in a sentence, a pronoun must also agree with the word it refers to. If the word is plural, its pronoun must be plural and vice versa. 


The teacher began her lesson.

All students should submit their projects before Friday.

The above examples use personal pronouns. These pronouns refer to a specific person, group or object. To read more about English pronouns, click here.

27. Dangling Modifiers

Which word a dangling modifier refers to is unclear. 

Example: Looking out the window, a tornado was forming.

This sentence implies that a tornado was looking out the window while it was forming! 

Absurd, right?

The correct sentence: Looking out the window, I saw a tornado forming. 

The easiest way to correct dangling modifiers is to put the modifier next to the term it refers to.

28. Split Infinitives

An infinitive is a word of the form “to” + a verb

Examples: to swim, to walk, to run.

When adverbs come between the to and the verb, it splits them apart, thus creating split infinitives. The most famous example of a split infinitive is from Star Trek: “To boldly go….”

While sometimes it can be right, avoid split infinitives in formal writing.

Example: Try to whenever possible avoid splitting infinitives. 

Sounds awkward, right?

The correct sentence: Try to avoid splitting infinitives when possible.  

29. Hyphen vs. Dashes

A hyphen (-) is used to:

  • Join compound words or parts of words such as prefixes, suffixes

Example: user-friendly, pre-colonial.

  • Group numbers like phone numbers

Example: 123-456-7890

  • Indicate breaks in words that wrap around a line break

Example: He was talk
-ing with his friend.

A dash is longer than a hyphen and usually indicates a pause or range. The two common dashes are the en dash (–) and the em dash (—). 

The em dash, often simply called the dash, is the most commonly used and most versatile of the dashes.

An en dash (–) is mostly used:

  • To indicate ranges in dates and numbers

Examples: pages 10–20, 2018–19, 2020–, August–September 2020

However, if the range is introduced with from, use to instead of an en dash.

Example: Obama was POTUS from 2009 to 2017.

  • With directions and scores

Example: Dublin–London flight, the Mets won 5–1.

An em dash (—) is mostly used:

  • To add emphasis or explanation especially when reflecting on an abrupt interruption in thought
  • In place of a comma to enhance readability

Example: The three of them—Peter, Joy and John—went to a party last night.

  • In place of parentheses

Example with parentheses: On discovering the missing artifacts (all 50 of them), he called the police.

Example with em dash: On discovering the missing artifacts—all 50 of them—he called the police.

Note: The comma or any surrounding punctuation is dropped after the parentheses are changed to em dash.

Another note: In British usage, an en dash (with space before and after) is usually preferred to the em dash as punctuation in running text, a practice that is followed by some non-British publications as well, according to the Chicago Manual of Style, seventeenth ed.

  • In place of a colon to emphasize the conclusion of the sentence. 

Example: After months of deliberation, the jurors reached a unanimous verdict—guilty.

30. Passive Voice

The passive voice occurs when the object in a sentence becomes the subject. 

Example: The ball was kicked by Jack. 

Here, the placement of the ball implies it functions as the subject, when it’s actually the object and receives the action.

Example of active voice: Jack kicked the ball.

Here, Jack is the subject, and the ball is the object. 

While passive voice masks the subject in a sentence, it also can make writing wordy

Here are a few other common grammar mistakes you should avoid:

  • Using double negatives 
  • Excessively employing prepositional phrases
  • Ending sentences with prepositions
  • Adding apostrophes to possessive nouns incorrectly

The Quickest Way To Avoid Grammar Mistakes: Use Grammar Checkers

Grammatical errors often create the impression of rushed writing or poor attention to detail, whether found in an article, ebook, social media post, email or any other content.

While errors can be tough to spot even if you proofread multiple times, online grammar checkers can help iron out the mistakes. 

Here are two tools you could use to produce grammatically correct content. 

I’m an affiliate for both products and use them regularly as part of my writing workflow. If you sign up, I’ll earn a small commission.

1. Grammarly

Grammarly is a popular writing tool that checks for English grammar errors and typos in any text. It offers specific settings for four English dialects––American, British, Canadian and Australian. 

Whether you’re a native speaker or someone who uses English as a Second Language (ESL), Grammarly can help you eliminate poor grammar.  

Key Features

  • Detects grammar mistakes, sentence fragments and more with real-time suggestions and guidelines to correct them
  • Displays a powerful spell checker for each English dialect
  • Analyses your writing for readability, clarity, overuse issues and more
  • Compares your writing to billions of web pages using a plagiarism detector
  • Helps you double-check if you’re using the right words or spellings when writing using its Google Docs integration

Read my detailed Grammarly review

2. ProWritingAid

ProWritingAid is an online editor and grammar checker that novelists, bloggers, and business professionals use. It analyses and reviews writing for readability, grammar errors and other inconsistencies.

While anyone can use it, ProWritingAid is better suited for fiction writers. 

Key Features

  • Identifies irregular verbs, wrong sentence structures, passive voice and more
  • Generates detailed reports that analyze every aspect of your writing
  • Auto-highlights words that can be replaced with a synonym
  • Provides a word explorer to help you find the right words

Read my detailed ProWritingAid review.

Avoid Common Grammar Mistakes Today

While following grammar rules is important, you shouldn’t let it stop you from finishing your next draft.

If you make a mistake and get called out, fix it and move on. Don’t let a grammar nazi have the last word.

Lots of great writing contains grammar issues. Sometimes grammar differences are a matter of style.

Just keep an eye out for the common errors I covered in this article to sharpen your writing skills and avoid the grammar police. With online grammar checkers like Grammarly and ProWritingAid, fixing grammatical errors and proofreading becomes a breeze!

If you want to learn more about grammar, here are some resources:

What are recurring common grammar or writing mistakes? Keep a list so you can learn. Or use a grammar book or some grammar checker software to fix them.

  • Bryan Collins is the owner of Become a Writer Today. He's an author from Ireland who helps writers build authority and earn a living from their creative work. He's also a former Forbes columnist and his work has appeared in publications like Lifehacker and Fast Company.