Translation guide
How to express that someone cannot do something, or lacks the ability to do something, in natural Japanese.
Expressing that someone cannot do something, or something is impossible.
The standard way to say 'cannot do V'. Polite form is ことができません.
私は泳ぐことができない。
I cannot swim.
彼は来ることができません。
He cannot come.
The potential negative form of verbs is very common in casual speech. For ru-verbs, replace る with られない; for u-verbs, change the ending to the え-row + ない.
A noun or na-adjective meaning 'impossible'. Often used in formal or written contexts.
その計画は不可能だ。
That plan is impossible.
Expressing that someone is not good at something, or lacks the ability due to insufficient skill.
Means 'to be bad at N'. N is a noun or nominalized verb (こと).
私は歌が下手です。
I am bad at singing.
Used with a verb to say 'bad at doing V'.
彼は料理を作るのが下手だ。
He is bad at cooking.
Means 'weak point' or 'not good at'. Softer than 下手, often implies a personal feeling of inadequacy.
Expressing that something cannot be done due to external circumstances, rules, or physical constraints.
Means 'must not do V' or 'it is not allowed to do V'. Used for prohibitions.
ここで写真を撮ってはいけない。
You must not take photos here.
Expresses that one cannot do something due to social or moral obligations, not just ability.
約束を破るわけにはいかない。
I cannot break my promise.
Expressing that one cannot do something because they lack the necessary tools, money, time, etc.
The same pattern as general inability, but often accompanied by a reason.
お金がないから、買うことができない。
I can't buy it because I have no money.
Casual way with potential negative form, often followed by から or ので.
時間がないから、行けない。
I can't go because I have no time.
Both mean 'cannot', but できない is more formal and explicit, while the potential negative form (e.g., 食べられない) is more common in casual speech. Use できない in writing or formal situations.
私は納豆が食べられない。
I can't eat natto.
私は納豆を食べることができません。
I cannot eat natto. (polite)
The English noun 'inability' is often best expressed with verb phrases in Japanese. Using a direct noun like 不能 (ふのう) is very formal and limited to specific contexts (e.g., 機能不全). Avoid translating 'inability' as a standalone noun.
I'm not good at math.