How do you use can for ability?

Put can in front of a bare verb: She can solder a joint. The form is the same for every subject, with no to and no -s. The negative is can't or cannot: She can't thread those eyelets. Questions invert can: Can you swim a length of backstroke?

When do I use be able to instead of can?

When can cannot inflect. After to (I'd like to be able to crochet), after will (She will be able to thread the eyelets), after another modal (You might be able to salvage the joint), and in perfect forms (He has been able to knead since he was twelve). In a simple present statement, can is the natural choice.

What is the difference between can and know how to?

Can names present performance: She can solder. Know how to names a learned method and inflects like an ordinary verb: She knows how to solder. They often mean the same, but they can split: I know how to swim butterfly; I just can't last a length yet. For most everyday skills, can is enough.

Is Can I leave the kiln on about ability?

No. That is permission: you are asking whether a rule allows the action. Ability would be Can you leave the kiln on?, asked of someone who might not know the switch, or I can't leave it on, said because the timer is broken. Permission questions with can, could, and may have their own page.

English grammar · Beginner

Can for Ability: Present Skill, Know How, and Be Able To

Written by Eleanor Whitfield, Lead English Curriculum Editor · Reviewed September 2026

Can and can't talk about present ability: what you know how to do, or what is possible for you now. She can solder. He can't swim a length of backstroke. Can does not take to, does not add -s, and does not have an infinitive or a past participle of its own, so English borrows be able to when a form of can cannot exist (I'd like to be able to crochet. She has been able to knead since she was twelve.). Can also asks for permission; that job has its own page.

She can solder a joint in under a minute, but she can't thread the tiny eyelets without a magnifier.

can for a present skill; can't for a present lack of skill

What it is

Can is the everyday modal for present ability. It sits in front of a bare verb and tells you that the subject has the skill, the strength, or the opportunity now: She can solder. He can juggle three beanbags. I can knead this dough with one hand. Can't (cannot in careful writing) is the negative: She can't thread those eyelets. Because can is a modal, it never takes to, never takes -s, and never follows another modal. When you need an infinitive, a participle, or a future form, you switch to be able to: She will be able to crochet after a few lessons. Know how to names a learned skill and is a useful extra, not a replacement for can.

I can swim a length of backstroke. (present ability) I can't swim a length of butterfly. (present lack) I'd like to be able to swim butterfly. (infinitive: can cannot follow to)

How to spot it

Look for can or can't plus a bare verb, talking about skill or possibility now. If the sentence is Can I leave the kiln on?, the job is permission, not ability. If the time is past, the form is could or was able to, which belong on a past-ability page.

She can solder a joint without burning the flux. (present skill)
He can't juggle with his left hand yet. (present lack of skill)
Can you knead this dough while I oil the tin? (ability question, also a request for help)
I can see the eyelets if I stand on the stool. (ability from opportunity, not a trained skill)

Can covers both trained skills (can solder) and opportunity (I can see the eyelets from here). Context tells you which. Permission uses the same form and is only sketched below.

Can for Ability Quick Reference

Can for ability: forms you actually need

Job	Form	Example
Present ability	can + bare verb	She can solder a joint.
Present lack	can't / cannot + bare verb	She can't thread the eyelets.
Question	can + subject + bare verb	Can you swim a length of backstroke?
Learned skill, extra clear	know how to + bare verb	He knows how to crochet a chain.
After to, after a modal, or in a perfect	be able to + bare verb	I'd like to be able to crochet.
Past (preview)	could / was able to	She could solder at sixteen. She was able to finish the joint.

Common Can for Ability Examples in English

Present ability first, then the two helpers English uses when can runs out of forms:

Present Ability with Can

She can solder a joint in under a minute.: a trained present skill
He can juggle three beanbags but not four.: ability with a clear limit
I can knead this dough with one hand.: present physical ability
The workshop can seat twelve at a pinch.: can of present capacity, not a person's skill

Can does not add -s: she can, never she cans. The next verb stays bare: solder, juggle, knead, not to solder.

Can't and Questions

She can't thread the tiny eyelets without a magnifier.: present lack of ability
I cannot for the life of me tie a surgeon's knot.: cannot is the full written form of can't
Can you swim a length of backstroke?: yes/no question about a skill
How well can he crochet a flat circle?: wh-question, can still before the subject

Answers echo the modal: Yes, I can. No, she can't. Do-support never appears: Does she can solder is not English.

Know How To

He knows how to crochet a chain, but he can't yet keep the tension even.: know how to for the method, can for the present result
Do you know how to tie a surgeon's knot?: asking about a learned method
She doesn't know how to quench the solder without cracking it.: lack of know-how, not lack of strength
I know how to swim butterfly; I just can't last a length yet.: knowledge of the stroke versus present stamina

Know how to is useful when you want to split knowledge from present performance. For most everyday skills, can alone is enough: She can solder.

Be Able To When Can Cannot Inflect

I'd like to be able to crochet a flat circle.: infinitive: to can does not exist
She will be able to thread the eyelets once the magnifier arrives.: future: will can is impossible
He has been able to knead since he was twelve.: present perfect: can has no participle
You might be able to salvage the joint if you reheat it.: after another modal: might can is impossible

In the simple present, can is the natural choice (She can solder). Be able to is possible there too, but it sounds heavier: She is able to solder. Save it for the forms can cannot make.

How Can for Ability Works

A modal with almost no forms of its own, and two helpers that fill the gaps.

Can Plus a Bare Verb, No -s, No To

Can is the same for every subject: I can, she can, they can. The next verb is the dictionary form with no to: can solder, not can to solder and not cans solder. The negative is can't in speech and cannot in careful writing. Questions move can in front of the subject: Can you juggle?

She can solder. Can she solder? She can't solder.

one form of can for statements, questions, and negatives

Can + base verb. Never to. Never -s.

Can Covers Skill and Opportunity

She can solder is a trained skill. I can see the eyelets from this stool is opportunity: the situation makes the action possible. Both are present ability. The workshop can seat twelve is capacity, a close cousin. You do not need a different verb for these readings; the rest of the sentence tells you which you have.

I can hear the kiln from the yard.

present opportunity, not a trained skill

Skill or situation: both can.

Be Able To Supplies the Missing Forms

Can has no infinitive, no -ing form, no past participle, and no future of its own. English uses be able to for those slots: to be able to crochet, being able to knead, has been able to solder, will be able to thread. After another modal the same switch happens: might be able to, should be able to. In a plain present statement, prefer can.

She has been able to knead since she was twelve.

present perfect needs be able to because can has no participle

Need to / will / have? Switch to be able to.

Know How To Names a Learned Method

Know how to plus a bare verb points at knowledge of a method. It is not a modal, so it inflects: she knows how to, she knew how to, she has known how to. Use it when you want to separate knowing the method from being able to perform it right now: I know how to swim butterfly; I just can't last a length yet.

He knows how to crochet a chain.

a learned method, present simple of know

Know how to = the method. Can = the present performance.

Past Ability Is a Different Page

Could is the past of can for general past ability (She could solder at sixteen) and for some past opportunities. Was able to often marks a single past success (She was able to finish the joint before the flux burned). This page stays with present ability. Follow the past-ability bridge when the time is yesterday.

She can solder now. She could solder at sixteen.

can for present, could as a preview of past ability

Now: can. Then: could / was able to.

Common Mistakes with Can for Ability

Incorrect: She can to solder a joint.

Correct: She can solder a joint.

Can takes a bare verb. To after it is the most common beginner error with modals, copied from want to and need to.

Incorrect: He cans juggle three beanbags.

Correct: He can juggle three beanbags.

Can has no -s form. She can, he can, it can: the same word for every subject.

Incorrect: I would like to can crochet a flat circle.

Correct: I would like to be able to crochet a flat circle.

Can has no infinitive. After to you need be able to. The same switch happens after will, have, and another modal.

Incorrect: Does she can swim a length of backstroke?

Correct: Can she swim a length of backstroke?

Can is already the auxiliary, so the question inverts it. Do and does are not added.

Be Able To and Know How To

Two helpers that sit around can, used when the modal cannot inflect or when you want to name a method.

Where be able to is required

Use be able to after to, after another modal, in the future with will, and in perfect forms. Can cannot occupy those slots.

I'd like to be able to crochet a flat circle.: after to
She will be able to thread the eyelets tomorrow.: future
You might be able to salvage the joint.: after another modal

She can be able to solder doubles the idea and is wrong. Choose can or be able to, not both.

Know how to versus can

Know how to names a learned method and inflects like an ordinary verb. Can names present performance. They often go together, and they sometimes split.

She knows how to solder, and she can do it quickly.: method plus present performance
I know how to swim butterfly; I just can't last a length yet.: method without present stamina
He doesn't know how to quench the solder.: the method is missing

For a simple present skill, can is enough. Add know how to when the method itself is the point.

Quick Check: Can for Ability

Complete each sentence with can, can't, or a form of be able to.

1. She ___ solder a joint in under a minute.

Answer: can

present skill, modal plus bare verb

2. He ___ thread the tiny eyelets without a magnifier.

Answer: can't / cannot

present lack of ability

3. ___ you swim a length of backstroke?

Answer: Can

question: can before the subject

4. I'd like to ___ crochet a flat circle.

Answer: be able to

infinitive slot: can has no to-form

5. She ___ knead since she was twelve.

Answer: has been able to

present perfect: can has no participle

Can for Ability FAQs

How do you use can for ability?: Put can in front of a bare verb: She can solder a joint. The form is the same for every subject, with no to and no -s. The negative is can't or cannot: She can't thread those eyelets. Questions invert can: Can you swim a length of backstroke?
When do I use be able to instead of can?: When can cannot inflect. After to (I'd like to be able to crochet), after will (She will be able to thread the eyelets), after another modal (You might be able to salvage the joint), and in perfect forms (He has been able to knead since he was twelve). In a simple present statement, can is the natural choice.
What is the difference between can and know how to?: Can names present performance: She can solder. Know how to names a learned method and inflects like an ordinary verb: She knows how to solder. They often mean the same, but they can split: I know how to swim butterfly; I just can't last a length yet. For most everyday skills, can is enough.
Is Can I leave the kiln on about ability?: No. That is permission: you are asking whether a rule allows the action. Ability would be Can you leave the kiln on?, asked of someone who might not know the switch, or I can't leave it on, said because the timer is broken. Permission questions with can, could, and may have their own page.
What is the past of can for ability?: Could for a general past skill: She could solder at sixteen. Was able to often marks a single past success: She was able to finish the joint before the flux burned. This page stays with present ability. Could as a polite Can I (Could I leave a message?) is permission, not past time.