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Common Grammar Mistakes to Avoid
Grammar Rules
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Common Grammar Mistakes to Avoid
In this article, we classified all common types of grammar mistakes you’ve heard about and never knew how to collect in one place.
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Published on
Mar 21, 2025
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Have you ever internally cringed from noticing your own mistakes in speaking or writing in English and being unable to change what you have said? Don’t worry; it is surely an issue for 1.52 billion English speakers worldwide, according to the numbers from the International Center for Language Studying.
Grammar mistakes occur often both for those studying a language and those who have spoken it their whole lives. However, letting them pass regularly in your speech and written text negatively impacts your image and professionalism.
In this article, we will cover the 25 most common grammar mistakes, each including two sub-types, leaving you with 50 mistakes to check. You can use the article as a minimal toolkit for fixing your grammar in only a few study sessions. As always, there is also StudyPro academic AI tool if you need more comprehensive support through your studying journey.
What Is Considered a Grammar Mistake?
Grammar mistakes is a broad term covering many different errors. In widest definition, a grammar mistake is an error in the structure or rules of a language that affects:
- Correctness
- Clarity
- Or the meaning of a sentence
The common misconception about grammar mistakes is that every deviation from the textbook rules is unacceptable, forcing each language user to strive for nothing less than perfection in using the language.
However, The Rolling Stones sing “I Can’t Get No Satisfaction,” and the double negative in the phrase doesn’t make fans love the song less. Some deviations from grammatical recommendations can show that the speakers are in a casual, relaxed environment or that error is an intentional stylistic choice.
As a general rule of thumb, you can identify a grammatical mistake if:
- The error confuses and twists the intended meaning
- The error is not justified by the context and harms the image of the speaker
Common Grammar Mistakes: the List
So, what are some common grammar mistakes to avoid?
Let’s categorize the whole confusing and complicated field of grammar into three easy-to-grasp categories:
→ Word choice mistakes
→ Common phrases errors
→ Sentence-building mistakes
This article will cover the most common ones in each category. There are more, but you can use this checklist as a basis and complete it with others further on:
Common Word Choice Mistakes
A great number of common grammar mistakes fall under the category of word errors - mixing up similar-sounding words, misspelling, or misusing terms. Let’s cover the first 9 types of common grammar errors in this block.
1. Mixing Up Similar-Sounding Words
Mixing Homophones
Homophones are words that sound identical but have different meanings.
Words Sound Identical | Examples |
|---|---|
Two/too/to |
3. This coffee is too hot! (identifying a quality) 4. We are going to the park. (direction) |
Weather/whether |
|
Mixing Heterographs
Heterographs are words that sound similar but have different meanings.
Words Sound Similar | Examples |
|---|---|
Lay/lie | I will lay the book on the table. (to put something down) I need to lie down for a nap. (to recline in a horizontal position) |
Affect/effect | The news will affect her deeply. (the action of having an impact) The new law had a positive effect on the economy. (a result or outcome) |
Then/than | First we will eat, then we will watch a movie. (time and sequence) She is taller than her brother. (comparisons) |
Farther/further | I need to walk farther to reach the station. (physical distance) We need to further investigate this issue. (abstract progress) |
2. Getting Apostrophes Wrong
Apostrophes are used to show possession (like "Mary's book") or to form shortened word forms (like "can't" for "cannot"). These two cases form much confusion, though.
Confusing Contractions and Possessive Pronouns
- Contractions are shortened forms of words (like "who’s" for "who is").
- Possessive pronouns are words that show ownership (like "whose car" referring to the car’s owner).
Pronouns | Examples |
|---|---|
Whose/who’s | Who’s coming to the party tonight? (contraction of "who is") Whose book is this? (possessive form of "who") |
Its/it’s | The dog wagged its tail. (possessive form of "it") It’s a beautiful day outside. (contraction of "it is") |
Their/they’re | Their house is on the corner. (possessive form of "they") They’re going to the beach tomorrow. (contraction of "they are") |
Your/you’re | Is this your pen? (possessive form of "you") You’re doing a great job! (contraction of "you are") |
Misplacing Apostrophes
The two most common grammatical errors with apostrophes are:
- Misplacing apostrophes while showing possession or referring to somebody in singular form,
- And misplacing apostrophes to refer to more than one person.
Example: The student’s book is on the desk. (possessive form of one student)
Example: The students’ papers are on the table. (possessive form of multiple students)
3. Missing Necessary Words
Students often omit essential words in their sentences. Here are two examples of grammar mistakes related to missing words.
Missing Prepositions
Prepositions are words that show relationships between other words (like "in," "on," or "under").
Incorrect: According the news, the weather will be cold.
Correct: According to the news, the weather will be cold.
Missing Articles
Articles are words that define a noun as specific ( "the") or unspecific ( "a," "an,").
Incorrect: I saw dog in the park.
Correct: I saw a dog in the park.
4. Misusing Latin Terms
The English language preserves the marks of its historical changes, including Latin roots. However, these marks are also grammatical stepping stones. Some common grammar mistakes in English come from misunderstandings of these historical influences, as happened with Latin-origin abbreviations.
I.e. vs. e.g
Abbreviations | Examples | Where to Use |
|---|---|---|
I.e. (“id est”, from Latin “that is”.) | She loves classical music, i.e., Beethoven and Mozart. | Use “i.e.” to clarify the statement. |
E.g. (“exempli gratia”, “for example” in Latin) | She enjoys outdoor activities, e.g., hiking and cycling. | Use “e.g.” to add new details. |
Etc. vs. et al.
Abbreviations | Examples | Where to Use |
|---|---|---|
Etc. (“et cetera.”, Latin “the rest”) | We need to buy fruits, vegetables, etc. | Use “etc.” in casual contexts. |
Et al. (“et alia,” Latin “and others”). | The research was conducted by Smith et al. | Preserve “et al.” for citing academic research. |
5. Misusing Article
Definite Article Mistakes
Definite article ("the") refers to a specific noun. The main cases for using definite articles are when referring to specific, known, or unique nouns, or when something has already been mentioned in separate sentences before.
Incorrect: I saw a dog in the park. A dog was very friendly.
Correct: I saw a dog in the park. The dog was very friendly.
Indefinite Articles Mistakes
Indefinite articles "a" and "an"refer to any noun, not a specific one. You may usually use indefinite articles in three cases:
- When referring to non-specific nouns
- Referring to singular countable nouns,
- Or when introducing something for the first time.
Incorrect: I want the apple.
Correct: I want an apple. (Here, "an apple" refers to any apple, not a specific one.)
6. Misuse of Expressions and Phrasal Verbs
The two most common grammar mistakes in translation are misusing idiomatic expressions and translating the phrases literally into another language.
Misusing Phrasal Verbs
Phrasal verbs are expressions made up of a verb and one or more particles. The thing about phrasal verbs is that if you change the particle, the whole sentence's meaning changes, too.
Incorrect: He picked into a new hobby.
Correct: He picked up a new hobby.
Translating Expressions Too Literally
Different languages have various ways of expressing the same thing. For example, in Spanish, the phrase “I’m cold” literally translates as “I have cold”. Thus, a direct literal translation often causes non-natural phrases, like:
Incorrect: I did a decision.
Correct: I made a decision.
7. Confusing Modal Verbs
Modal verbs are auxiliary verbs that express ability, possibility, necessity, or permission. The two most common confusion cases happen when using can/could and may/might in past contexts.
Can vs. Could
In reported speech, make sure to match the tenses of the main verb and the modal verb.
Incorrect: He said he can finish the project tomorrow.
Correct: He said he could finish the project tomorrow.
May vs. Might
You can use "may" to ask for permission or express possibility in the present or future. Instead, "might" expresses a lower possibility or refers to a hypothetical situation in the past.
Incorrect: She said she may go to the party last night.
Correct: She said she might go to the party last night.
8. Mixing Up Parts of Speech
Parts of speech are the basic categories of words; the categories of these words stand on their function in a sentence. There are eight main parts of speech: nouns, pronouns, verbs, adjectives, adverbs, prepositions, conjunctions, and interjections.
Respectively, there are up to sixteen different scenarios for common grammatical errors to arise. Here are two examples:
Adjective vs. Adverb Confusion
Incorrect: She sings beautiful.
Correct: She sings beautifully.
Noun vs. Verb Form Confusion
Incorrect: His decision to success in business was inspiring.
Correct: His decision to succeed in business was inspiring.
9. Misforming Compound Words
Compound words are the combinations of two or more words that create a new meaning. Common mistakes usually arise when the writer contemplates using a hyphen and writing words as one or as two words.
Hyphen-Related Errors
Incorrect: She gave a last minute presentation.
Correct: She gave a last-minute presentation. ("Last-minute" is a compound adjective and should be hyphenated.)
One Word vs. Two Words Confusion
Incorrect: The children are playing outside the school yard.
Correct: The children are playing outside the schoolyard. ("Schoolyard" is a compound noun and should be written as one word.)
What are some common mistakes in English grammar? It’s confusing "your" vs. "you're", and thinking that everyone notices when you do.
Common Phrases Errors
The next level, after the misuse of separate words, is common mistakes in phrases, redundant structures, and word combination errors. Let’s look at 7 more common mistake categories.
10. Redundancy in Sentences
Redundancy occurs when the author uses unnecessary repetition of words or ideas.
Repetition of Synonyms
Incorrect: The teacher gave a free gift to the students.
Correct: The teacher gave a gift to the students. ("Gift" already implies it’s free, so "free" is redundant.)
Pleonasms (using more words than necessary)
Incorrect: He caught the ball with his two hands.
Correct: He caught the ball.
11. Mismatching Pronouns
Incorrect pronouns make sentences sound awkward or make your readers question what you’re trying to say. The most common mistakes in using pronouns happen when you don’t match these words in number, gender, and case with the nouns they replace.
I vs. Me
Incorrect: The teacher gave my brother and I a book.
Explanation: In this case, "I" is incorrect because it is the object of the verb "gave." The correct pronoun in the object position is "me."
Incorrect: The teacher gave my brother and me a book.
Explanation: In this case, “me” is correct because it is the subject to the action - being given the book.
Correct: My brother and I went to the cinema.
Explanation: In this case, "I" is correct because it is an object that performs the action - going to the cinema.
Unclear Reference
Incorrect: When Mary talked to Linda, she was upset. (Who was upset?)
Correct: When Mary talked to Linda, Linda was upset.
12. Wrong Use of Infinitives and Gerunds
Infinitives (the base form of the verb with “to”) and gerunds (the "-ing" form) are often confused when deciding which form to use after certain verbs. Here are two examples of what could go wrong:
Misuse of Infinitives
Incorrect: He suggested to go to the park.
Correct: He suggested going to the park. (After "suggest," use the gerund form.)
Misuse of Gerunds
Incorrect: I enjoy to swim in the pool.
Correct: I enjoy swimming in the pool. (After "enjoy," a gerund is required, not an infinitive.)
13. Punctuation Errors
Punctuation marks are important as they help clarify meaning. Correctly placed commas help to separate ideas and indicate pauses in writing. At the same time, missing commas, periods, or incorrect use of parentheses can sometimes lead to one threatened to be eaten.
Missing Commas
Incorrect: Let's eat daddy.
Correct: Let's eat, daddy. ( The small “ it’s only a comma” issue changes the meaning from inviting someone to eat to suggesting them being eaten)
Overuse of Commas
Incorrect: I went to the store, and, I bought some milk, and, then I went home.
Correct: I went to the store and bought some milk, then I went home.
14. Confusing That, Which, and Who
“That,” “which,” and “who” are collectively called relative pronouns, but each of the pronouns has distinct uses. Here are the examples of common mistakes with these pronouns:
Using "That" Instead of "Who" for People
Incorrect: The man that helped us was very kind.
Correct: The man who helped us was very kind. (Use “who” when referring to people.)
That vs. Which
The tricky matter with choosing between “that” and “which” is deciding what information is essential to the meaning. Here’s how to differentiate between the two:
Relative Pronouns | Examples | Explanation |
|---|---|---|
That | The book that I borrowed is excellent. | The sentence is talking about the borrowed book, so it is essential information. |
Which | The book I borrowed, which has a blue cover, is excellent. | The information about the color of the cover is non-essential, so we use “which”. |
15. Dangling Parts of the Sentence
Participle is a verb form ending in "-ing" or "-ed". The participle is called dangling when it is not attached to the main object in the sentence. Here are some examples for clarity.
Unattached Parts of the Sentence
Incorrect: Running to catch the bus, the rain started. (Was the rain running to catch the bus?)
Correct: Running to catch the bus, I got soaked in the rain.
Misleading Sentences
Incorrect: Looking out the window, the flowers were blooming.
Correct: Looking out the window, I saw the flowers blooming.
16. Either/Or, Neither/Nor
Such words as “either”, “or”, “neither”, and “nor” are called correlative conjunctions. They help to connect parallel sentence elements. A common mistake is using them inconsistently or pairing them with incorrect verb forms.
Incorrect Subject-Verb Agreement
Incorrect: Either the manager or the employees is responsible for the project delay.
Explanation: The verb “is” is singular but stands next to the plural “employees”.
Correct: Either the manager or the employees are responsible for the project delay.
Explanation: The verb agrees with the closer subject, "employees."
Inconsistent Pairing
Incorrect: She likes neither coffee or tea.
Explanation: Incorrect correlative pairs are used here.
Correct: She likes neither coffee nor tea.
Explanation: The correct correlative pair is "neither/nor."
Common Sentence-Building Mistakes
Finally, some of the most confusing grammatical rules regulate the sentences in the English language. Here are 9 more common mistake types.
17. Subject-Verb Agreement
Subject-verb agreement means that the subject and verb in a sentence must match in number. Singular subjects need singular verbs, while plural subjects require plural verbs.
Singular/Plural Confusion for Collective Nouns
Incorrect: The group of students were excited about the field trip.
Correct: The group of students was excited about the field trip.
Somebody/nobody/anybody
Incorrect: Everybody in the rooms were asked to leave.
Correct: Everybody in the rooms was asked to leave.
18. Run-On Sentences
A run-on sentence occurs when you try to connect two different ideas without proper connection means. The grammatically correct ways to join sentences are through proper punctuation or connecting words. Here are two most common categories where the mistakes happen:
Fused Sentences
Incorrect: She loves to read she has hundreds of books.
Correct: She loves to read, and she has hundreds of books.
Comma Splices
Incorrect: The weather was beautiful, we decided to go for a walk.
Correct: The weather was beautiful, so we decided to go for a walk.
19. Forming Questions Incorrectly
Questions in English follow specific word order patterns. For example, in some cases forming questions requires auxiliary words (be, can, could, dare, do, have, may, might, must, need, ought, shall, should, will, would), and in some cases it doesn’t.
Here are two main types of mistakes to avoid:
Word Order Confusion
Incorrect: Why you are leaving so early?
Correct: Why are you leaving so early?
Misusing Auxiliaries
Auxiliaries | Examples | Explanation |
|---|---|---|
Do/Does/Did | ❌ Incorrect: You like coffee? ✅ Correct: Do you like coffee? | Use with most present and past tense questions that don't have another auxiliary or "be" verb. |
Is/Am/Are/Was/Were | ❌ Incorrect: Does she coming to the party? ✅ Correct: Is she coming to the party? | Use when asking about states, conditions, or continuous actions using "be" verbs. |
20. Making Faulty Comparisons
Faulty comparison means that the compared parts do not belong to the same logic category or that the comparison is incomplete.
Illogical Comparison
Incorrect: Her car is faster than her driving skills. (Illogical because "faster" describes speed, while "driving skills" refer to ability.)
Correct: Her car is faster than any she has driven before.
Incomplete Comparison
Incorrect: This computer is faster and more efficient.
Correct: This computer is faster and more efficient than our previous one.
21. Parallel Structure Errors
Parallel structure means using the same pattern of words for two or more ideas that have the same level of importance. Grammar mistakes happen when the speaker uses different forms of the words while building a parallel structure, like using gerund and infinitive in one logical sequence.
Mixed Verb Forms
Incorrect: She enjoys swimming, hiking, and to play tennis.
Correct: She enjoys swimming, hiking, and playing tennis.
Inconsistent Structures in Lists
Incorrect: The benefits include flexible hours, a good salary, and you can work from home.
Correct: The benefits include flexible hours, a good salary, and the ability to work from home.
22. Using the Wrong Tense
Verb tense errors occur when the time frame is not consistently maintained throughout a sentence or paragraph. Here are some examples:
Shifting Tenses Unnecessarily
Incorrect: He studies every night and passed the exam last week. (uncoordinated present tense and past tense within one sentence)
Correct: He studied every night and passed the exam last week.
Incorrect Sequence of Tenses
Incorrect: She said that she is tired. (uncoordinated present tense and past tense within one sentence)
Correct: She said that she was tired.
23. Double Negatives
Double negatives occur when two negative words or constructions are used in the same clause. It is similar to math, where two negatives cancel each other out. In English, though, such canceling leads to confusion or the opposite of the intended meaning.
Using Multiple Negative Words
Incorrect: I don't have no money.
Correct: I don't have any money.
Negative Words with Negative Verbs
Incorrect: He couldn't find his keys nowhere.
Correct: He couldn't find his keys anywhere.
24. Incorrect Conditional Sentences
Conditional sentences are one of the most confusing topics for non-native English speakers. These constructions involve expressing hypothetical situations and their consequences, both requiring different tenses and verb forms. This complexity produces many mistakes, the most common of them being:
Mixed Conditionals
Incorrect: If it will rain tomorrow, we will cancel the trip to the Alps.
Correct: If it rains tomorrow, we will cancel the trip to the Alps.
Explanations:
→ The first conditional (future possible) requires simple present tense in the if-clause ("rains") and future tense ("will cancel") in the result clause.
→ Uses proper forms with simple present tense in the if-clause and future tense ("will") in the result clause.
25. Word Order
Finally, one more common mistake is ignoring the fact that word order in English always follows specific patterns. Unlike some languages, where you can mix the words in the sentence without a significant meaning loss, this is not the case for the English language.
Non-native speakers struggle with mixing many word placements, but here are the most common ones:
Adverb Placement
Incorrect: She arrives always late to work.
Correct: She always arrives late to work.
Noun Placement
Incorrect: He bought for his mother a gift.
Correct: He bought a gift for his mother.
Improving Grammar in Three Days (a Guide)
Working on basic grammar rules is usually the least favorite task for students, scholars, and just almost everyone on Earth. However, there is a way to deal with it once and never come back to revising the topic seriously again.
Here’s a 3-day check-list to cover your specific grammar mistakes:
Day 1.
✔️ Write a few texts. Choose a topic you like, lock yourself in a comfortable room with no distractions, and free-write from 5 to 10 pages.
✔️ Feed your writing to AI. For example, ask Chat GPT to carefully examine your texts, analyze the grammar errors, and categorize them.
✔️ Write down your findings. Transfer the lists of your specific mistakes to any comfortable document, written or printed.
Day 2.
✔️ Learn the basic rules. You need to understand why the rule exists and why you made the mistake in the first place.
✔️ Search for as many examples as possible. It is best if the examples present different contexts and use situations.
✔️ Use active recalling to memorize the rules. Try to recall the examples you collected in the process.
Day 3.
✔️ Prompt AI to quiz you. For example, ask it to write a text using the grammar structures you’ve mistaken and leave the blanks for you to fill in.
✔️ Prompt AI to write an essay task for you. Ask it to write the list criteria of what grammar constructions must appear at least once in your writing.
✔️ Write the text and analyze it. You can also use a grammar checker by StudyPro to proofread your text. Have you repeated any of the previous mistakes?
Sum Up
Grammar mistakes happen to the best of us—whether it’s a misplaced comma or a sentence that spirals into a never-ending run-on. However, all of them are easy to fix once you know what to look for.
Think of grammar as a trusty roadmap rather than a rigid set of rules. The better you navigate it, the clearer and more natural your writing becomes. The only most important rule when handling common grammar mistakes is remembering that nobody expects your sheer perfection.
Frequently asked questions
The most common grammar mistakes in English usually include missing, misusing, or confusing some grammar forms. The most common ones among English users are confusing similar-sounding words, misusing articles, and misusing modal verbs.
Here are the examples of 10 errors students make when writing:
- Failing to form agreements between independent clauses
- Writing run-on sentences
- Using sentence fragments
- Misusing apostrophe
- Misplacing modifiers
- Making incorrect verb tense or active and passive voice agreements
- Using redundancies
- Confusing homophones
- Misforming compound words
- . Mismatching pronouns
Usually, the most confusing grammar topic is forming conditionals as it requires keeping an eye on all sentence parts and agreeing different tenses and verb forms.
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