Translation guide
How to express doing something alone, without help, or independently in Japanese. The best choice depends on whether you mean 'alone' (solo), 'without help' (on one's own), or 'automatically' (by itself).
I live by myself.
I did it by myself.
To do something without other people, solo.
The most common and neutral way to say 'by oneself' meaning alone. Used for actions done solo.
He lives by himself.
I went to see a movie by myself.
Same as 一人で but with the kanji 独, which emphasizes solitude or loneliness. Slightly more literary or emphatic.
I like traveling by myself.
Literally 'just by oneself', emphasizing no one else is involved. Can overlap with 'without help'.
Don't decide by yourself.
To do something independently, without assistance.
The standard way to say 'by oneself' meaning without help. Emphasizes doing something personally.
Do your homework by yourself.
He cooked by himself.
Emphasizes using one's own power or ability, often for overcoming difficulties. More formal or determined nuance.
He solved the problem by himself.
Similar to 自力で but more literary. Means 'by one's own efforts'.
He started the business by himself.
Something happens on its own, without external cause.
Used for things that happen spontaneously or automatically, like a door closing by itself.
The door closed by itself.
The wound healed by itself.
Means 'naturally' or 'by itself' in the sense of without human intervention. Often used for processes.
The problem resolved itself.
Means 'automatically', often for machines or systems, but can be used figuratively.
Updates are performed by themselves.
一人で (hitori de) means 'alone' (solo), while 自分で (jibun de) means 'by oneself' (without help). Use 一人で when emphasizing the absence of others, and 自分で when emphasizing independence or personal effort.
Saying 自分で映画を見た (jibun de eiga o mita) sounds like you watched a movie without help, not that you went alone. Use 一人で for solo activities.