Translation guide
Expresses that something is not surprising given the circumstances. Japanese uses several patterns depending on formality and emphasis.
To say that something is not surprising, often after learning the reason.
A common, casual way to say 'no wonder' when you realize the reason for something. Often used at the beginning of a sentence.
No wonder he was late.
Literally 'I see', but often used to express 'no wonder' when something makes sense. Can be combined with other phrases.
Attached to a clause explaining the reason, meaning 'it's no wonder that...'. Often used with どうりで.
More formal/literary. Means 'it's only natural that...'.
No wonder he's angry.
Means 'it's no wonder that...' or 'it's understandable that...'. Slightly more empathetic.
No wonder he's tired.
どうりで directly expresses 'no wonder' after learning a reason. なるほど is more like 'I see' and can be used alone, but when combined with だから or わけだ it also conveys 'no wonder'.
なるほど、だから彼は来なかったのか。
No wonder he didn't come.
He's lived in Japan for 10 years, so no wonder his Japanese is good.
A: He pulled an all-nighter last night. B: No wonder he looks sleepy.