14 Common Grammatical Mistakes in English – And How to Avoid Them

Source: Oxford Royale Academy

A huge number of native English speakers make frequent English slip-ups that bring on the wrath of the UK’s army of grammar pedants, and it’s mainly because they weren’t taught properly at school. But for you, help is at hand. So that you can learn the rules from the word go, we’ve put together this guide to some of the most common mistakes people make when writing in English. Learn them all, and you’ll get your knowledge of English off to a better start than most Brits! Even if you’re a native speaker, you may find some useful advice here to make your use of English the best it can be.

1. Misplaced apostrophes

Apostrophes aren’t difficult to use once you know how, but putting them in the wrong place is one of the most common grammar mistakes in the English language. Many people use an apostrophe to form the plural of a word, particularly if the word in question ends in a vowel, which might make the word look strange with an S added to make it plural.

The rules:

Apostrophes indicate possession – something belonging to something or someone else.

To indicate something belonging to one person, the apostrophe goes before the ‘s’. For instance, “The girl’s horse.”

To indicate something belonging to more than one person, put the apostrophe after the ‘s’. For example, “The girls’ horse.”

Apostrophes are also used to indicate a contracted word. For example, “don’t” uses an apostrophe to indicate that the word is missing the “o” from “do not”.

Apostrophes are never used to make a word plural, even when a word is in number form, as in a date.

How not to do it:

The horse’s are in the field

Pen’s for sale

In the 1980’s

Janes horse is over there

The girls dresses are ready for them to collect

How to do it properly:

The horses are in the field

Pens for sale

In the 1980s

We didn’t want to do it

Jane’s horse is over there

The girls’ dresses are ready for them to collect

2. Your/you’re

We covered this one before in our post on homophones, but it’s such a widespread problem that there’s no harm in covering it again.

The rules:

“Your” indicates possession – something belonging to you.

“You’re” is short for “you are”.

How not to do it:
Your beautiful

Do you know when your coming over?

Can I have one of you’re biscuits?

How to do it properly:

You’re beautiful

Do you know when you’re coming over?

Can I have one of your biscuits?

3. Its/it’s

We said earlier that apostrophes should be used to indicate possession, but there is one exception to this rule, and that is the word “it”. Unsurprisingly, this exception gets lots of people confused.

The rules:

“It’s” is only ever used when short for “it is”.

“Its” indicates something belonging to something that isn’t masculine or feminine (like “his” and “hers”, but used when you’re not talking about a person).

If it helps, remember that inanimate objects can’t really possess something in the way a human can.

How not to do it:

Its snowing outside

The sofa looks great with it’s new cover

How to do it properly:

It’s snowing outside

The sofa looks great with its new cover

4. “Could/would/should of”

This common mistake arises because the contracted form of “could have” – “could’ve” – sounds a bit like “could of” when you say it out loud. This mistake is made frequently across all three of these words.

The rules:

When people write “should of”, what they really mean is “should have”.

Written down, the shortened version of “should have” is “should’ve”.

“Should’ve” and “Should have” are both correct; the latter is more formal.

How not to do it:

We could of gone there today

I would of done it sooner

You should of said

How to do it properly:

We could’ve gone there today

I would have done it sooner

You should’ve said

5. There/their/they’re

We’ve met this one before, too; it’s another example of those pesky homophones – words that sound the same but have different meanings.

The rules:

Use “there” to refer to a place that isn’t here – “over there”.

We also use “there” to state something – “There are no cakes left.”

“Their” indicates possession – something belonging to them.

“They’re” is short for “they are”.

How not to do it:

Their going to be here soon

We should contact they’re agent

Can we use there boat?

Their is an argument that says

How to do it properly:

They’re going to be here soon

We should contact their agent

Can we use their boat?

There is an argument that says

6. Fewer/less

The fact that many people don’t know the difference between “fewer” and “less” is reflected in the number of supermarket checkout aisles designated for “10 items or less”. The mistake most people make is using “less” when they actually mean “fewer”, rather than the other way round.

The rules:

“Fewer” refers to items you can count individually.

“Less” refers to a commodity, such as sand or water, that you can’t count individually.

How not to do it:

There are less cakes now

Ten items or less

How to do it properly:

There are fewer cakes now

Ten items or fewer

Less sand

Fewer grains of sand

7. Amount/number

These two work in the same way as “less” and “fewer”, referring respectively to commodities and individual items.

The rules:

“Amount” refers to a commodity, which can’t be counted (for instance water).

“Number” refers to individual things that can be counted (for example birds).

How not to do it:

A greater amount of people are eating more healthily

How to do it properly:

A greater number of people are eating more healthily

The rain dumped a larger amount of water on the country than is average for the month

8. To/two/too

It’s time to revisit another common grammar mistake that we also covered in our homophones post, as no article on grammar gripes would be complete without it. It’s easy to see why people get this one wrong, but there’s no reason why you should.

The rules:

“To” is used in the infinitive form of a verb – “to talk”.

“To” is also used to mean “towards”.

“Too” means “also” or “as well”.

“Two” refers to the number 2.

How not to do it:

I’m to hot

It’s time two go

I’m going too town

He bought to cakes

How to do it properly:

I’m too hot

It’s time to go

I’m going to town

He bought two cakes

9. Then/than

Confusion between “then” and “than” probably arises because the two look and sound similar.

The rules:

“Than” is used in comparisons.

“Then” is used to indicate something following something else in time, as in step-by-step instructions, or planning a schedule (“we’ll go there then there”).

How not to do it:

She was better at it then him

It was more then enough

How to do it properly:

She was better at it than him

It was more than enough

We’ll go to the baker first, then the coffee shop

10. Me/myself/I

The matter of how to refer to oneself causes all manner of conundrums, particularly when referring to another person in the same sentence. Here’s how to remember whether to use “me”, “myself” or “I”.

The rules:

When referring to yourself and someone else, put their name first in the sentence.

Choose “me” or “I” by removing their name and seeing which sounds right.

For example, with the sentence “John and I are off to the circus”, you wouldn’t say “me is off to the circus” if it was just you; you’d say “I am off to the circus”. Therefore when talking about going with someone else, you say “John and I”.

You only use “myself” if you’ve already used “I”, making you the subject of the sentence.

How not to do it:

Me and John are off to the circus

Myself and John are going into town

Give it to John and I to look after

How to do it properly:

John and I are off to the circus

John and I are going into town

Give it to John and me to look after

I’ll deal with it myself I thought to myself

11. Invite/invitation

This mistake is now so common that it’s almost accepted as an alternative, but if you really want to speak English properly, you should avoid it.

The rules:

“Invite” is a verb – “to invite”. It refers to asking someone if they’d like to do something or go somewhere.

“Invitation” is a noun – “an invitation”. It refers to the actual message asking someone if they’d like to do something or go somewhere.

How not to do it:

I haven’t responded to her invite yet.

She sent me an invite.

How to do it properly:

I haven’t responded to her invitation yet.

She sent me an invitation.

I’m going to invite her to join us.

12. Who/whom

Another conundrum arising from confusion over how to refer to people. There are lots in the English language!

The rules:

“Who” refers to the subject of a sentence; “whom” refers to the object.

“Who” and “whom” work in the same way as “he” or “him”. You can work out which you should use by asking yourself the following:

“Who did this? He did” – so “who” is correct. “Whom should I invite? Invite him” – so “whom” is correct.

“That” is often used incorrectly in place of “who” or “whom”. When referring to a person, you should not use the word “that”.

How not to do it:

Who shall I invite?

Whom is responsible?

He was the only person that wanted to come

How to do it properly:

Whom shall I invite?

Who is responsible?

He was the only person who wanted to come

13. Affect/effect

It’s an easy enough mistake to make given how similar these two words look and sound, but there’s a simple explanation to help you remember the difference.

The rules:

Affect is a verb – “to affect” – meaning to influence or have an impact on something.

Effect is the noun – “a positive effect” – referring to the result of being affected by something.

There is also a verb “to effect”, meaning to bring something about – “to effect a change”. However, this is not very commonly used, so we’ve left it out of the examples below to avoid confusion.

How not to do it:

He waited for the medicine to have an affect

They were directly effected by the flooding

How to do it properly:
He waited for the medicine to have an effect

They were directly affected by the flooding

14. I.e. and e.g.

These two abbreviations are commonly confused, and many people use them interchangeably. However, their uses are very different.

The rules:

I.e. means “that is” or “in other words”. It comes from the Latin words “id est”.

E.g. means “for example”. It comes from the Latin words “exempli gratia”.

Only use “i.e.” and “e.g.” when writing informally. In formal documents, such as essays, it is better to write out the meanings (“for example” or “that is”).

How not to do it:

He liked many different cheeses, i.e. cheddar, camembert and brie.

He objects to the changes – e.g. he won’t be accepting them.

How to do it properly:

He liked many different cheeses, e.g. cheddar, camembert and brie.

He objects to the changes – i.e. he won’t be accepting them.


We hope you’ve found this a useful reference guide as you continue your journey to become fluent in English.