• 2-minute read
• 20th February 2021

Spelling Tips: Cannot, Can Not or Can’t?

Is the proper way to write “can’t” in full “cannot” (one word) or “can not” (two words)? And when should you use these terms in your writing? In this post, we explain the basics of when (and how) to use these words in your writing.

Cannot and Can’t

First, let’s define our terms: “cannot” is the opposite of “can.” We therefore use it when something is not possible or not permitted. For instance:

He cannot run as fast as a cheetah.

You cannot come in here without a pass.

“Can’t,” meanwhile, is a shortened version of “cannot”:

He can’t run as fast as a cheetah.

You can’t come in here without a pass.

As a rule, contractions like “can’t” are fairly informal. Thus, if you are writing something formal, such as a student essay or business report, use “cannot.”

The Error: Can Not

Most contractions featuring “not” are written out in full as two words:

Didn’t = Did not

Shouldn’t = Should not

Isn’t = Is not

Some people thus assume the full version of “can’t” is “can not” (two words). But this is a mistake! As noted above, the correct spelling is “cannot” (one word):

He cannot be serious! ✓

He can not be serious! ✗

There are some occasions when “can” may precede “not” as part of a phrase. For instance, “can” is fine before the phrase “not only… but also”:

He can not only juggle but also ride a unicycle!

But if you are just forming a negation, “cannot” is always a single word.

Summary: Cannot, Can Not or Can’t?

So, when should you use these terms? To summarize the key points:

• Cannot is the proper negative form of “can.”
• Can’t is a contraction of “cannot” often used in informal writing.

Writing “can not” (i.e., as two separate words) is almost always an error, though, so keep an eye out for this in your work! Alternatively, if you’d like someone to check your writing for errors with an expert eye, try our proofreading services today.