要等多久？

You can use this phrase exactly as it is. It is a complete sentence. If you want to be specific, add the event at the start. For example, 吃饭要等多久？ means 'How long to wait for the meal?' You can also add 还要 (still need) to the front. 还要等多久？ sounds like you are getting a bit impatient. It is like saying 'How much longer now?'

Use this at a busy restaurant with a line. Use it at the doctor's office when your appointment was 20 minutes ago. It is perfect for asking a friend who is 'five minutes away' for the third time. Use it at a bus stop or a train station. It is a survival phrase for anyone living in a crowded city. It helps you decide if you should stay or go.

Do not use this if you are the one being waited on. That would be confusing and a bit rude! Avoid using it in very high-stakes formal ceremonies. In those cases, ask for a 'schedule' instead. Don't use it if the time is already clearly posted. You might look like you aren't paying attention. Also, don't bark it at service staff. A little smile goes a long way with this question.

In China, waiting in line is a national pastime. From famous milk tea shops to hospital registrations, lines are everywhere. Asking 要等多久？ is a social necessity. It is how people gauge the 'worth' of an experience. If the wait is two hours for hotpot, is it really that good? This phrase is your tool for navigating the 'queue culture' of modern Chinese life.

You will often hear 等多久？ which is just a shorter version. If you want to be very polite, start with 请问 (May I ask). 请问要等多久？ is the gold standard for politeness. If you are in a rush, you might say 还要多久？ which is even more direct. It translates to 'How much longer?' and implies you have places to be.