Telling the time: giờ, phút, rưỡi, kém

Asking the time: Mấy giờ rồi?

Mấy giờ rồi? is the everyday way to ask what time it is. You already know mấy from the numbers unit: it asks for a small number, and a clock face never goes past twelve, so mấy is exactly the right question word here. giờ is the hour, and rồi at the end belongs to this fixed question as a whole – take the four syllables as one phrase for now. The longer version is Bây giờ là mấy giờ?, where bây giờ means 'now'. To an older person, add ạ at the end, exactly as you did when asking someone's age.

Answering: the number goes in front of giờ

For a whole hour, say the number and then giờ: hai giờ is two o'clock, mười giờ is ten o'clock. A full sentence puts Bây giờ là in front of it. No number changes shape here: one o'clock is một giờ and never mốt, because there is no mười or mươi standing in front of it.

Minutes follow the hour and carry the word phút behind them: ba giờ mười lăm phút is 3:15, and sáu giờ hai mươi mốt phút is 6:21. The sound changes from the numbers unit still apply, because a real mười or mươi is standing in front: fifteen minutes is mười lăm, twenty-one minutes is hai mươi mốt. In quick speech phút is often dropped once it is obvious that minutes are meant.

Bây giờ là ba giờ mười lăm phút.It is a quarter past three.

Half past and the minutes before: rưỡi and kém

rưỡi is 'and a half' and it stands right after giờ: năm giờ rưỡi is half past five. Never put a number after it – the half is already the thirty minutes. kém works the other way round and means 'short of': you name the hour you are heading towards, then kém, then the minutes still missing. So bảy giờ kém mười is ten minutes to seven, that is 6:50. Vietnamese normally uses kém only from about twenty minutes before the hour; anything earlier is simply counted forward from the hour that has struck.

No a.m. and p.m.: sáng, trưa, chiều, tối

A Vietnamese clock only counts to twelve, so the part of the day does the work that a.m. and p.m. do – and it comes after the hour, not before it: bảy giờ sáng is seven in the morning, tám giờ tối is eight in the evening. With the word buổi in front, the same words name the stretch of day on their own: buổi sáng, buổi chiều, buổi tối. Timetables, news and station announcements use the twenty-four hour clock instead, and then no part of the day is added at all: mười chín giờ is 19:00.