N5
なくちゃ・なきゃ
Must do, Have to do
野菜を食べなくちゃいけない。
I must eat vegetables.
Explanation
「〜なくちゃ」 and 「〜なきゃ」 are the most common spoken forms of 'must …':
1「〜なくちゃ」 is a contraction of 「〜なくては」.
2「〜なきゃ」 is a contraction of 「〜なければ」.
The full form is followed by 「いけない」, 「ならない」 or 「だめだ」, but in speech people often say only the first half: 「もう行かなきゃ」 (I have to go now).
Mixed up with
Speech only: with peers, friends and family, or to yourself. In formal situations, with elders and in exam writing, restore it to 「〜なくてはいけません」 or 「〜なければなりません」.
It shows up in almost every listening test, so react instantly: 「なくちゃ＝なくては」, 「なきゃ＝なければ」.
「〜なきゃ」 is very common among young people and sounds casual and a bit cute.