Translation guide
Expressing inability to perform an action in Japanese, using potential forms, negative potential, and other constructions.
Expressing that one cannot do something, in a neutral sense.
The most common way to say 'cannot do'. Use the negative of the potential form of the verb. For ru-verbs, replace 〜る with 〜られない; for u-verbs, change the final -u to -e and add ない; for する, use できない; for くる, use こられない.
A more formal or written way to express inability. Literally 'the thing of doing is not possible'. Used with any verb.
彼は泳ぐことができない。
He cannot swim.
The standalone 'cannot do', often used when the verb is clear from context. Also used as 'I can't' in casual speech.
宿題ができない。
I can't do my homework.
Emphasizing that one does not have the skill or ability to do something.
Same as general inability, but often with adverbs like 上手に (skillfully) or うまく (well).
上手に料理が作れない。
I can't cook well.
Literally 'doing is unskillful'. A softer way to say you are not good at something.
私は歌うのが下手だ。
I'm not good at singing.
Expressing that something cannot be done because of external factors, not lack of ability.
Still the most natural way, but context makes it clear it's due to circumstances.
雨で出かけられない。
I can't go out because of the rain.
Used when you cannot do something due to social obligation, moral reason, or principle. 'It wouldn't be right to...'
約束を破るわけにはいかない。
I can't break my promise.
More formal, often used in written explanations of impossibility.
この機械は修理することができない。
This machine cannot be repaired.
Expressing that one is not permitted to do something.
Standard way to say 'must not' or 'cannot' in the sense of prohibition. Often used in rules.
ここで写真を撮ってはいけない。
You can't take photos here.
Can imply prohibition in a formal context, similar to 'it is not permitted to...'
ここで喫煙することはできません。
You cannot smoke here.
Expressing that one cannot do something due to emotional or psychological reasons.
Literary expression meaning 'cannot bear to do'. Used for actions that would cause emotional pain.
彼女の顔を見るに忍びない。
I can't bear to look at her face.
Used to express a feeling that one cannot do something, often due to hesitation.
どうしても彼に言えない気がする。
I just feel like I can't tell him.
For ru-verbs, the potential form and passive form are identical (e.g., 食べられる can mean 'can eat' or 'be eaten'). Context usually clarifies, but be aware of the ambiguity.
このキノコは食べられる？
Can we eat this mushroom? / Is this mushroom eaten?
For する verbs, the potential is できる. For other verbs, the potential form is more common in speech than ことができる, which sounds more formal.