Yap.Town

게 얼마나

how ... is

→ 것+이
phrase Rare #20,464
how ... is Used to emphasize the degree or amount of something; the exact translation depends on what comes before and after it.
KO: 이게 얼마나 중요한지 알아?
EN: Do you know how important this is?

제일 길게 사귄 게 얼마나 돼요?

What’s the longest you’ve ever been in a relationship?

— The Chaser (2008)