Korean grammar · Level 4 · 4급
V/A-기 마련이다 (-게 마련이다)
It's bound to be so — a rule of life
at Level 3 you described what a person tends to do with -(으)ㄴ/는 편이다. Now you want the stronger claim: 'this is simply how things go, for everyone'. That is the voice of advice, proverbs and essays.
Example
사람은 나이가 들면 기억력이 나빠지기 마련이에요.
As people get older, their memory is bound to get worse.

The full explanation is in the unit · part of the Level 4 Pass, opening soon · Level 4, Unit 4
Judging and generalising
The rule with a table, Sori’s tips, practice that checks itself, a review room and a one-page cheat sheet.
See the unit preview →