Formal:
* Que horas são? (pronounced: keh oh-ras saun) - This is the most common and formal way to ask the time.
Informal:
* Que horas são? (pronounced: keh oh-ras saun) - This is also the most common and informal way to ask the time.
* Que horas é? (pronounced: keh oh-ras eh) - This is slightly less common and is used in more informal settings.
Other options:
* Pode me dizer que horas são? (pronounced: poh-dj me di-zehr keh oh-ras saun) - "Could you tell me what time it is?" (more polite)
* Você sabe que horas são? (pronounced: vo-seh sah-beh keh oh-ras saun) - "Do you know what time it is?" (more casual)
Remember that the time in Portuguese is always stated in the 24-hour format. For example, 1:00 PM is 13:00 and 9:00 PM is 21:00.