- 悔不当初 huǐbùdāngchū deeply regretto regret one's past deeds
- 罚不当罪 fábùdāngzuì disproportionatethe punishment does not fit the crime, typically implying that it is more severe than deserved
- 万夫不当 wànfūbùdāng invinciblehaving such great courage and strength that one can withstand ten thousand men; peerless in valor
- 不当得利 bùdàngdélì unjust enrichment
- 不当紧 bùdāngjǐn unimportantnot important or of no consequence
- 说话不当话 shuōhuàbùdànghuà break promiseTo fail to keep to one's word or renege on what one has said.
- 不当一回事 bùdàngyīhuíshì disregardTo not take something seriously; to regard as unimportant.
- 不当事 bùdāngshì disregardto treat something as trivial or not worth serious attention
- 不当家不知柴米贵 bùdāngjiābùzhīcháimǐguì unaware of costsa person who doesn't manage a household would not be aware how expensive it is