"I'm sorry, I have an appointment."

Translation: 不好意思，我有一个约会。

[Keith_APP]

Just a note which I think can be useful. 约会 usually would imply a date, although the basic meaning is just a meeting, usually casual, such as between friends (as is in the present sentence, which has no problem). For a business meeting or appointment for service, especially the latter, it seems a little strange to say 约会. An alternative for such cases is 預約.

[awunker]

Is there a reason "对不起" is not accepted for "Sorry"?

[George418878]

It should be accepted. Report it!

[malinshka]

"一個" is unnecessary. It's too literally translated.

[RobinThor]

一個 is the traditional for 一个 by the way, in case anyone else wonders.

[RobinThor]

Is the 一个 needed? Would 不好意思我有约会 also be okay?

[LaBiciEsMia]

"对不起，我有一个约会" still not accepted, 13 August 2018.

[YoungSiger]

不好意思，我有约了

[froggie3802]

对不起我有一个约会. Still not accepted. January 9, 2019

[GaMic2018]

You don't need "一" here.

[itsaash]

对不起 should also be accepted...

[Ling_G23]

In real life Chinese, 约会 only means date, you go on it with the one you are in a romantic relationship with, while 预约 is any type of appointments you have with others.

[Aprilharian]

thank you for your explanation!

[Ling_G23]

You are welcome

[WilliamH77559]

The Chinese people I know say that "yuehui" is more of a date than an appointment. Anyone else heard this?

[Ling_G23]

Yes, if you say you have a "yuehui" with your doctor, others would understand that you are dating with your doctor. I'm a native speaker.

[SparkitEle]

不好意思 我有一个约会
marked as wrong, i dont know why

[14minx14]

對不起，我有一個約會 13th of May 2019, still not accepted. reported.

[whsndstalb]

lol i accidentally wrote 約定