22 common grammar mistakes that make you look really stupid

The way that you write can have a big impact on your success, especially in the corporate working world. The fewer mistakes you make, the smarter you look. 

As a writer who spent 14-years working in corporate America, I’ve seen every mistake in the book. While nobody is perfect, the more that we can avoid easier mistakes that make us look stupid, the better our chances of getting that next promotion

Here is a look at more than 20 grammar mistakes that could be harming your career. 

22 grammar mistakes that make you look stupid

1: Your vs. You’re

If you are constantly using “your”, then you are committing one of the most common grammar errors. “Your” shows possession, while “you’re” is a contraction that means “you are”. 


  • Your dog is adorable
  • You’re doing a great job

2: Its vs. It’s

“Its” is possessive, while “it’s” is a contraction of “it is”. Many people use the “it’s” version incorrectly. The next time you use “it’s”, mentally read that part of the sentence as “it is” to confirm that you are using the correct version of the word. 


  1. I put my keys in its container. 
  2. It’s getting cold outside.

3: There vs. Their vs. They’re

Commonly mixed up, “there” refers to a place, “their” shows possession, and “they’re” is a contraction of “they are”. 


  • There isn’t too much more to do
  • Their house is beautiful
  • They’re doing a great job

4: Affect vs. Effect

Perhaps one of the easiest grammar errors to make, “affect” is a verb while “effect” is a noun. Use the former to refer to the act of changing and the latter to refer to the change itself. 


  • That experience had a big effect on me
  • That experience affected me a lot

5: Me vs. I

The difference between “Me” and “I” is deceiving. Many people incorrectly use “I” when the appropriate word is “me. 

“I” should not be used when it refers to the object of a sentence. For example, “Please report back to Sally and I” is incorrect for the same reason why “Please report to I” is wrong. Using the word “me” is the right way to write that sentence. 


  • Please report back to Sally and me
  • Sally and I need to be kept updated on your progress

6: To vs. Too

Use “Too” as another word for “also” or to describe something that is extreme, and “to” before either a noun or a verb. 


  • Sorry, I am too busy today 
  • I am walking to the bus stop

7: i.e. vs. e.g.

Another common grammar mistake, there is a big difference between these two terms. 

Use “i.e.” to say “in other words” or “that is”, and “e.g.” to mean “for example”. 


  • I love seafood (e.g., sushi)
  • I loved your gift (i.e., the watch)

8: Who vs. Whom

Here, we are talking about the difference between a pronoun (“who”) and someone who will be the recipient of something. 


  • To whom should this letter be addressed?
  • Who knocked over that glass of water?

9: Who vs. That

This subtle mistake is all too easy to make. When describing an object, use “that”. When describing a person, use “who”. 


  • His car is the one that looks like a boat!
  • You should go talk to that person who looks very fit

10: Into vs. In to

Believe it or not, there is a very real difference between these two terms. Use “into” to describe some type of movement (i.e., moving “into” a new house). Use “in to” in most other situations that reference other parts of the sentence. 


  • Next week, we are moving into a house house
  • I just came in to warm up a little bit

11: Then vs. Than

These two words have very different meanings. Use “than” in reference to a comparison, and “then” to specify timing. 


  • My car is much less expensive than yours
  • I went to the grocery store, and then I dropped by the gas station

12: Lose vs. Loose

The adjective “Loose” refers to the opposite of “tight”. As in, “loose-fitting”. “Lose”  is a verb that refers to the opposite of “win”. As in, “I hate to lose”. “Lose” can also refer to misplacing something. 


  • These jeans are much too loose on me
  • I always lose my car keys!

13: Of vs. Have

Another easy mistake to make, use “have” when avoiding the use of the “should’ve”, “could’ve” or “would’ve” contractions. For instance, “I would of done better on the test if I studied more” is grammatically incorrect.  


  • We should have started dinner much earlier 
  • I could have scored better if I studied more

14: Less vs. Fewer

Use the term “fewer” when you can physically count the items and “less” when you can’t. 


  • I have fewer vacation days left than I had thought
  • I should have eaten much less dinner tonight 

15: Immigrate vs. Emigrate

Emigrate is a term that refers to leaving your country for another. Immigrate, on the other hand, is the act of entering another country. Use “emigrate” when the following word is “from” and “immigrate” when followed by “to”. 


  • My dad emigrated from Spain
  • My dad immigrated to the United States

16: “I could care less”

I have seen this a lot, and it makes no sense. When we write a sentence like this, we mean that we could NOT care any less. 


  • I could not care less
  • I couldn’t care less

17: Irregardless

Irregardless is not a word, so don’t use it. The term that you are looking for is “regardless”. 

18: Starting a sentence with “me”

We learn early on that putting the term “me” before a reference to someone else is incorrect. Yet, this still happens way too much. For instance, “Me and Steve went to the ballgame yesterday.” is grammatically incorrect. 


  • Steve and I went to the ballgame yesterday

19: Shoe-in

This is not a word unless you are referring to something inside a shoe, maybe? The word that you’re probably looking for is “shoo-in”, as in, a sure winner or a foregone conclusion. 

20: Peaked my interest

I see this one a lot, and the word “peaked” is incorrect. The appropriate word in this context is “piqued”, as in “Piqued my interest”. 

21: Worse comes to worse

“Worse” is the wrong word to use in this context. The proper word is “Worst”, as in, “Worst comes to worst”. 

22: A mute point

The correct word to use is “moot”, not mute. We are not referring to a point that has no volume, right? No, we are referring to a point that has no meaning or is irrelevant. As in, “A moot point”.