どんぶり勘かん定じょう

noun

rough estimate; sloppy accounting; slapdash bookkeeping

Refers to careless financial management or rough calculations without attention to detail. Often used in business or personal finance contexts to criticize lack of precision.

• 彼かれの経けい理りはどんぶり勘かん定じょうで、いつも赤あか字じだ。

  His accounting is slapdash, and he's always in the red.

• どんぶり勘かん定じょうで予よ算さんを立たてると、後あとで困こまることになる。

  If you make a budget with rough estimates, you'll run into trouble later.