Translation guide
Expressing that an action occurs by chance, coincidence, or unexpectedly. Japanese uses several patterns depending on whether it's a chance encounter, an accidental action, or a coincidental timing.
たまたま彼に会った。
I happened to see him.
たまたまそれを見つけた。
I happened to find it.
The subject does something without planning, often meeting or encountering someone/something.
The most common and neutral way to say 'happen to do' for chance events. たまたま is an adverb meaning 'by chance' or 'coincidentally'.
駅でたまたま友達に会った。
I happened to meet a friend at the station.
たまたまその店を見つけた。
I happened to find that shop.
More formal or written than たまたま. 偶然 means 'by coincidence' or 'accidentally'.
偶然彼の秘密を知ってしまった。
I happened to learn his secret.
Used for 'there are times when something happens', implying occasional chance occurrences. Not a direct translation but conveys a similar idea in certain contexts.
たまに道でばったり会うことがある。
I sometimes happen to run into him on the street.
The subject does something without intending to, often with a negative outcome.
For careless mistakes or actions done without thinking. Implies the action was unintentional and often regrettable.
うっかり秘密を話してしまった。
I happened to blurt out the secret.
うっかり電車を乗り過ごした。
I happened to miss my stop.
For actions done impulsively or against better judgment, often with a sense of 'I couldn't help it'.
つい食べ過ぎてしまった。
I happened to overeat (without meaning to).
Auxiliary verb indicating an action is done completely, often with a nuance of regret or unintended result. Often combined with other adverbs.
大事な書類を捨ててしまった。
I happened to throw away an important document.
Two events coincide, or something is discovered to be the case by chance.
Used to describe a situation where one action leads to a chance discovery or coincidence.
電話したら、たまたま彼が家にいた。
When I called, he happened to be home.
Similar to above but slightly more formal/literary with 偶然.
外を見ると、偶然彼が通りかかった。
When I looked outside, he happened to be passing by.
Expressing that someone happens to possess something or be in a state coincidentally.
For states or possession. たまたま modifies the stative verb.
たまたまその本を持っている。
I happen to have that book.
彼はたまたま医者だった。
He happened to be a doctor.
The verb 起こる (okoru) means 'to occur' or 'to happen' in the sense of an event taking place. It cannot be used to say 'I happened to do something'. Use adverbial expressions like たまたま or 偶然 instead.
事故が起こった。
An accident happened.
Both mean 'by chance', but たまたま is more colloquial and common in speech. 偶然 is slightly more formal and often used in writing or when emphasizing coincidence. They are often interchangeable.