Translation guide
The English word 'able' is most commonly expressed in Japanese through potential verb forms, the phrase ことができる, or adjectives like 可能な. The best choice depends on whether you're talking about ability, possibility, or a state of being capable.
I am able to speak Japanese.
He is an able student.
Expressing that someone has the skill, capacity, or opportunity to perform an action.
Japanese verbs have a special potential form that directly means 'can do' or 'is able to do'. This is the most natural and common way to express ability. For ru-verbs, replace る with られる; for u-verbs, change the final vowel to its え-row equivalent and add る. Irregular verbs: する → できる, 来る → 来られる.
I am able to speak Japanese.
He can swim.
A more formal or written way to express ability. It literally means 'the thing of doing V is possible'. It can be used with any verb, but in casual speech the potential form is preferred.
He is able to speak English.
A noun or na-adjective meaning 'possible' or 'feasible'. Often used in compounds or formal contexts. Not used alone to say 'I am able to...'.
Expressing that a situation allows an action, or permission is granted.
The potential form also covers circumstantial ability and sometimes permission. Context makes it clear.
Will you be able to come early tomorrow?
Describing someone as competent, skilled, or talented.
Expressing ability to see, hear, etc.
For 'can see', use 見える (spontaneous, without effort) or 見られる (potential of 見る). For 'can hear', use 聞こえる (spontaneous) or 聞ける (potential).
I am able to see Mt. Fuji. (It is visible.)
a feasible plan
Used specifically for permission: 'it's okay to do'. Not for ability.
Am I able to take photos here? (Is it allowed?)
A na-adjective meaning 'able', 'capable', 'competent'. Used for people.
He is an able lawyer.
The potential form of する, often used as an adjective meaning 'competent' or 'good at one's job'.
an able employee
I am not able to hear the sound.
I am able to speak Japanese. (more formal)
While 可能 means 'possible', it is not used to say 'I am able to do something' in the same way as the potential form. Saying 私は日本語が可能です is unnatural. Use the potential form or ことができる instead.