The Ultimate Guide to Using "Can" And "Be Able To"

Table of Contents

Though similar, "can" and "be able to" are different in three important ways:

They mean slightly different things
One is more common in formal English
One is more flexible grammatically

This post will explain each of these differences so you can use them both confidently in your English conversations.

Differences in Meaning

“Can” has more uses than “be able to”

"Be able to” has only one function: to talk about ability.

Are you able to attend the meeting tomorrow?
You won't be able to use this app until you update your phone's operating system.

"Can," however, has many functions.

Ability: “I can speak English.”
Possibility: “It can get hot in this room.”
Permission: “You can leave now.”
Request: “Can you come here, please?”

For example, the question “Can you come to my party tomorrow?” could mean both “Are you able to come?” and “Is it possible for you to come?”

Use “be able to” with subjects that have abilities

Learners sometimes make sentences like “Tickets are able to be purchased online” or “This product is able to be used in a microwave.”

However, in these examples, it sounds like the tickets and the product have abilities. Since objects do not have abilities, though, this is incorrect.

"Can” is better in these cases.

Tickets can be purchased online.
This product can be used in a microwave.

Differences in Formality

1. “Can” is more common in everyday conversations

Both "can" and “be able to” are used in casual conversations, and you can usually use either without changing a sentence's meaning.

For example, if a friend invited you to a party, you could reply with either of the following sentences:

I don’t know if I can come to your party.
I don’t know if I’ll be able to come to your party.

However, "be able to" sounds a little more formal, so it's common for people to use "can" most of the time.

Basically, if you want to emphasize ability (instead of possibility), use "be able to." In other situations, you can simply use "can."

2. “Be able to” is more common in formal English

In formal English, especially in writing, it’s usually better to be specific. This is why you’ll see “be able to” more often than “can” in news articles that mention ability.

You’ve probably also seen “be able to” in error messages when you’re using a computer. For example, if you have trouble buying something online, you might see messages like these:

We are unable to process your request at this time. Please try again later.
We are having difficulty processing your payment, so we are unable to proceed with your order.

In addition to being more specific, “be able to” also sounds more indirect and impersonal than “can.” For example, you’ve probably also received emails that say something like this:

Please do not reply to this email, as we are unable to respond from this address.

In situations like these, “unable to” sounds more polite than “cannot.”

Grammatical Differences

1. “Can” and "be able to" can be different in the past tense

“Could” and “was able to” are used to talk about abilities people had in the past. For example, the two sentences below mean the same thing.

When your grandma was young, she could eat five hamburgers in one meal.
When your grandma was young, she was able to eat five hamburgers in one meal.

And here are two sentences in the negative about the past that have the same meaning.

I couldn’t sleep last night.
I wasn’t able to sleep last night.

But when we want to talk about past abilities involving a specific incident, things get tricky. For example, try to put the following sentence in the past tense.

Sally can find a job in New York after graduating.

You might think “Sally could find a job … ” is the answer, but the "could" here is not the past tense of "can" — instead, it's the conditional form (“Sally could find a job if she tried”).

The correct answer is: "Sally was able to find a job in New York after graduating."

You can also say, "Sally could have found a job in New York after graduating" if she had the ability to get a job there but didn't for some reason (for example, maybe she chose to work in another city).

So when you’re talking about past abilities, pay extra attention to the choice between "can" and "be able to"!

2. Use “be able to” for future abilities

If you want to talk about future abilities, use “be able to.”

My daughter will be able to walk in a few months.
If I take lessons on Engoo, I will be able to speak English confidently.

If you just want to talk about future plans, “can” is better.

I can come to your party tomorrow.

3. Use “be able to" after other verbs

Since “can” is a modal verb, it can’t be used after other verbs. This is why the following sentences use “be able to.”

Applicants must be able to speak fluent French.
I want to be a nurse because I want to be able to help people who are sick.

4. “Be able to” can be used with other tenses too

As a modal verb, “can” doesn't have a continuous (-ing) form or a perfect form. So when you need to use these tenses, use “be able to.”

I wonder what it’s like not being able to swim.
She’s feeling better and has been able to eat a lot more lately.

Your Turn

Here’s a quick summary to help you review.

“Can” is used most of the time in casual conversations.
“Be able to” is more specific to ability.
“Be able to” is more flexible — it can be used with any verb and tense!
“Was able to” is used for (one-time) events in the past that happened, and “could have + past participle” for ones that didn't.

Now it’s time to practice! The following sentences all have a mistake. Try to find them.

Your email is unable to be delivered.
You don't need to can read music to learn guitar.
I have not can log into Instagram since last night.
The Great Wall of China is unable to be seen from the moon.
Applicants must can speak fluent French.

To find out the answers, book a lesson on Engoo! Engoo has thousands of tutors available any time of day and plenty of free materials you can study with. Give it a try!