遅刻 / 遅い when we wanna say “Hey hurry up! you'll be late!” which would be more appropriate?

Question

when we wanna say "Hey, hurry up! you'll be late!" which would be more appropriate?:

1. 遅刻するぞ！
2. 遅くなるぞ！
3. ？

Answer 1

遅刻するよ！ is the phrase you're looking for. 遅くなる does literally mean "become late", but this "late" is more along the lines of an event becoming delayed or postponed beyond the expected time. The context you're looking for is a person being late for a scheduled event, which is what 遅刻 conveys.

Either 遅刻するよ！ or 遅刻しちゃうよ！ can be used. The latter adds an undertone of regret.

遅れる works as an alternate for 遅刻する, if you want to avoid 漢語: 遅れちゃうよ！

And depending on the speaker and situation, ぞ can be substituted for よ, which was covered in this question.

Answer 2

What about 遅れるよ！ ？　I hear 遅れちゃった a lot when people show up to events.

Answer 3

I‘m no sure if people would say {遅刻するぞ}, because they might say {遅刻しちゃうぞ} instead. To 遅刻する is to be tardy intentionally, while 遅刻しちゃう, which comes from {遅刻してしまう} has the connotation that even though you don't have the intention, you might end up being tardy, thus you better hurry.

I'm a bit undecided between 遅くなるぞ and 遅刻しちゃうぞ so I'll leave to native speakers or those who live long in Japan to give their verdicts :)

Answer 4

The second one is good, and you can add 急いで (いそいで) to it to say "Hurry up"

急いで！遅くなるよ。

You can use 遅刻する as "to be late". It has a more specific meaning (late for school, an appointment). So if you're saying "Hurry up, you'll be late for school", say

急いで！遅刻するよ。or 急いで！遅刻になるよ。