。
I weighed myself on the bathroom scale.
Literal
Bathroom [possessive-の] scale [with-で] body-weight [object-を] measured.
秤 ('scale / balance') is a tool noun. 体重 ('body weight') is a compound 体 ('body') + 重 ('heavy'). 計る ('to measure') is used for weight, time, length — one of a set of 'measure' verbs (計る, 測る, 量る) that specialize slightly by domain but are often interchangeable.