〜となると

Usage

「-という場合には」when it comes to ~; if it is the case that ~ (then…); used to show that a certain condition leads to a particular reaction or judgment

時々掃除するならいいけど、毎日となると大変だ Cleaning occasionally is fine, but when it comes to doing it every day, it’s tough.

練習の時はいいけど、試合となると、いつも力が発揮できない It’s fine during practice, but when it comes to actual matches, I can never perform well.