Translation guide
How to express uncertainty in Japanese, from vague guesses to formal doubt.
The speaker is unsure about something and wants to convey that feeling.
A common pattern meaning 'I don't know whether...'. Attach to a plain form clause.
I'm not sure whether he will come.
I'm not sure if that's true.
Means 'uncertain' or 'unreliable'. Often used in formal or written contexts.
Literally 'I have no confidence', used to express uncertainty about one's own knowledge or ability.
I'm not confident about that answer.
Expresses possibility or uncertainty, like 'might' or 'maybe'. Attach to plain form.
It might rain.
Talking about an external state of uncertainty, not just personal feeling.
Used in writing, news, or technical discussions to denote uncertainty.
The noun form meaning 'uncertainty', common in academic or economic contexts.
Using adverbs to convey a sense of uncertainty in a statement.
Means 'probably' or 'maybe', a very common way to express uncertainty.
The English noun 'uncertainty' is often best expressed with verbs or adjectives in Japanese, like わからない or 不確かだ. Using the noun 不確実性 is mostly for formal writing.
たぶん is an adverb meaning 'probably', while かもしれない is a sentence-ending pattern meaning 'might'. They can be combined: たぶん〜かもしれない.
He might probably come.
結果はまだ不確かです。
The outcome is still uncertain.
Means 'opaque' or 'uncertain', often used for future prospects or situations.
The economic outlook is uncertain.
Means 'indeterminate' or 'uncertain', used in technical or formal contexts.
There are many uncertain factors.
Means 'not clear' or 'vague', used for situations or information.
His attitude is uncertain.
We need to reduce uncertainty.
Similar to 不確実性 but more often used in physics or philosophy (e.g., Heisenberg's uncertainty principle).
uncertainty principle
It's probably okay.
More formal than たぶん, means 'probably' or 'likely'.
He probably won't come.
Means 'perhaps' or 'possibly', often used with かもしれない.
Perhaps it might rain.