What's the difference between 一度に and 一気に?


Both can mean "all at once," so are they interchangeable or is there a
different nuance to each?




一気に is like saying “in one breath” and it always describes the quickness of
some action, while 一度に is more like “at a time” in the sense of "per time" or
“not on separate occasions”, and it says nothing about the duration. It may
just happen to be a short time.

> 彼は一気に水を３杯飲んだ。  
>  He drank three glasses of water in one go.

> 彼は一度に水を３杯飲む。  
>  He drinks three glasses of water at a time (= per time).

