also: むねざんよう
noun, noun or participle which takes 'suru'
rough mental estimate; calculating in one's head
Refers to making a rough calculation or estimate mentally, often without precise figures. Can be used as a noun or with する.
旅費を胸算用する。
I make a rough estimate of the travel expenses in my head.
胸算用では足りると思ったが、実際は予算
I thought it would be enough by my rough mental calculation, but in reality it was over budget.
noun, noun or participle which takes 'suru'
Used for expectations or anticipations, often with a nuance of hopeful or wishful thinking. Less common than the 'rough estimate' sense.
彼の胸算用は外れて、がっかりした。
His expectations were off the mark, and he was disappointed.