Translation guide
Expressing inability to perform an action in Japanese. The most common pattern uses the potential form of verbs, often with できない or other negative potential forms. There are also set phrases and grammar patterns for formal or written contexts.
Express that one is unable to perform an action due to lack of ability, circumstances, or permission.
The most common way to say 'cannot do' is to use the negative potential form of a verb. For ru-verbs, replace る with られない; for u-verbs, change the final -u to -e and add ない. する becomes できない, and くる becomes こられない.
I can't read kanji.
I can't wake up early in the morning.
He can't swim.
The negative potential form of する (to do). Used for 'cannot do' in a general sense, or when the verb is する.
I can't do my homework.
A more formal or written pattern meaning 'cannot do'. It uses the nominalizer こと to turn the verb into a noun phrase, followed by ができない.
He cannot eat natto.
A literary or formal pattern meaning 'cannot possibly do'. Attaches to the masu-stem of verbs. Often used in written language.
That's impossible. / That can't be.
Express that one is unable to do something because of a situation, rules, or external factors, not personal ability.
Used to say that one must not do something, or that it is not allowed. Often implies a prohibition or rule.
Express that no matter how hard one tries, the action cannot be accomplished.
Emphasizes that even if one attempts the action, it is impossible. Often used with どうしても or いくら...ても.
Express that one is emotionally or mentally unable to do something.
Literary expression meaning 'cannot bear to do'. Used for strong emotional inability.
できない is the casual, everyday form. ことができない is more formal and often used in writing or polite speech. Both express inability, but ことができない can sound more objective or definitive.
He can't swim. (casual)
I can't speak Japanese.
そんなことできない。
I can't do such a thing.
I cannot drive a car.
His success cannot be hoped for.
You cannot take photos here.
You must not sleep during class.
Means 'cannot do' due to social, moral, or situational constraints. It implies that doing so would be against one's principles or the situation does not allow it.
I can't break my promise.
I can't give up here.
Same pattern as above, but used when the inability is due to external factors rather than personal skill.
We can't play the match because of rain.
I just can't remember.
No matter how much I practice, I can't do it well.
Means 'there is no way to do' or 'cannot be done'. Indicates a lack of method or means.
This machine cannot be fixed.
There's no way to know where he went.
That sight is unbearable to watch.
Softens the statement by expressing a feeling of inability, often used for psychological reasons.
I feel like I can't go to work today.
彼は泳ぐことができない。
He cannot swim. (formal)
English 'be unable to' is often translated directly as できない or potential negative. However, in Japanese, the potential form itself already carries the meaning of ability/inability, so adding extra words like 不能 is usually unnatural.
He is unable to come.
She couldn't come to the party.
We cannot accept this proposal.