Structure
[な]Adjective + に + なる
[い]Adjective[く]+ なる
Noun + に + なる
Exceptions:
いい → よくなる
Details
- Expression 
- Verb 
- Standard 
About ~になる・~くなる
になる (with な-Adjectives), or くなる (with い-Adjectives) is an expression used in Japanese to show that something is 'becoming (A)'. It can be used with any form of なる, to highlight that something will become (non-past), is becoming (continuous), or has become (past). It can even be used with negative forms, to show that something 'will not become (A)'.
In the example with the tea getting cold, we can see how ている sometimes highlights something that exists in an ongoing state, rather than changing any further. In other words, 'the tea has gotten cold, and remains to be cold'.
Additionally, the adjective いい 'good' is an exception to the regular conjugation rules for い-Adjectives, and will conjugate as よくなる, not いくなる.
Related
Examples
--:--
- 難しくなる。 - To become difficult. 
- 嬉しくなる。 - To become happy. 
- 早くなる。 - To become fast. 
- よくなる。 - To become better. 
- 綺麗になる。 - To become pretty/clean. 
- Get more example sentences!- Premium users get access to 12 example sentences on all Grammar Points. 
Self-Study Sentences
Study your own way!
Add sentences and study them alongside Bunpro sentences.
- Online
- Offline- Genki I- Page 196 
- Genki I 2nd Edition- Page 234 
- Marugoto Elementary 2 (A2) Rikai- Page 149 
- Tae Kim's Japanese Grammar Guide- Page 129 & 130 
- みんなの日本語 I- Page 122 [CH 19] 
 
- Track Resources!- Bunpro tracks all of the resources you’ve visited, and offers relevant bookmarks of physical books to help with offline tracking. 
~になる・~くなる – Grammar Discussion
Most Recent Replies (46 in total)
 - Fuga - The difference between 冷たくなっているよ and 冷たくなったよ is the nuance and similar to how ‘has become’ and ‘became’ have a slight difference in nuance. 冷たくなっているよ has the nuance of ‘it has become cold’, and 冷たくなったよ has the nuance of ‘it became cold’. With 冷たくなっているよ the tea is still in the process of getting cold, while with 冷たくなったよ, just focuses on the fact that it got cold sometime in the past. - To express ‘the tea is (in the state of) getting cold’, 冷たくなっている would be best to use! 
 I hope this clears it up!
 - tzj 
 - IcyIceBear - Volitional form of しまう 
Got questions about ~になる・~くなる? Join us to discuss, ask, and learn together!
Join the Discussion