-니만큼 is a verb ending made up of the -니 ending and 만큼, an adverb functioning like a conjunction -니 expresses a reason or background (since, as) for the phrase following it. It's a short form of -니까. .e.g. - 벌써 12월이니(까) 금년도 얼마 안 남았다 = It's already December, which means there aren't many days left in this year. - 내가 갔다 올 테니(까) 넌 여기서 기다려 = I'll be off and back. You wait for me here. 만큼 as a noun means the same quantity or degree as something else. - 이만큼(this much), 그만큼(that much), 충분할 만큼(as much as needed), 남을 만큼(enough and then some). In a more abstract sense, 만큼 is an adverb for "to the extent", "given that ...", or "inasmuch as ...". - 최선을 다한 만큼 후회는 없다 = We have done our best, so there is no regret. - 그가 최대 고객인 만큼 특별히 대우해야 한다 = Inasmuch as he's our biggest client, we should treat him specially. -니만큼 combines -니 and 만큼. It gives a logical reason or justification for something. Compare it with the two other cases below. -니만큼 is equivalent to to -ㄴ 만큼, but sounds more explanatory. * -ㄴ 만큼 - observes an existing fact or principle to support one's argument. * -ㄹ 만큼 - relates a fact, possibility, or a hypothetical/potential situation to support one's argument. .e.g. 1. 학교가 머니만큼 [먼 만큼, 머니(까)] 일찍 나가야 한다. 2. 회사를 세웠으니만큼 [세운 만큼, 세웠으니(까)] 이제 열심히 일해야 된다. 3. 아기가 깰 만큼 큰 소리가 났다. (noise loud enough to wake the baby. Based on a real event used for effect, not fact) 4. 죽을 만큼 아팠다 = It was painful enough to kill me (-ㄹ 만큼 based on an improbable, rhetorical expression) (The difference between the -ㄴ and -ㄹ verb endings are part of the general verb conjugation rules)

Hi~Nayoon~ I'm going to explain it by an example. 할 만큼 means the amount of something to do from now to the future. 한 만큼 means the amount of something to have done. I hope it will help you enough.