Using the word ‘when’ in Indonesian is a little bit different from English. First, you have to choose which ‘when’ can be used in the context of your sentence. Second, you have to decide how you will convey your message: is it formal or informal? Third, you have to identify in what time frame you are going to refer your message: is it the present or the past?

Here are the samples:

• Use ‘Kapan’ to ask a question word about ‘when’ in English.
  • Kapan Anda pergi ke Jakarta? When will you go to Jakarta?
  • Kapan Beliau pulang? When is he/she going home?

Note: 

When you use ‘kapan’, you can leave out the ‘akan’, which means ‘will’ in Indonesian as it is understood.  The complete sentence would be “Kapan Anda (akan) pergi ke Jakarta?”

• Use ‘Kapan’ if the question is indirect (i.e. inside a sentence).
  • Saya tidak tahukapan dia pulang. I don’t know when they are going home.
  • Saya tidak tahukapan saya akan lulus sekolah. I am not sure when I will graduate.
• Use ‘Ketika’ and ‘waktu’ as conjunctions.
  • Saya sedang mandiketika dia menelepon saya. I was taking a shower when he called (me).
  • Telepon berderingwaktu saya masuk rumah. The phone was ringing when I entered the house.
• Use ‘Waktu’ to mean ‘time’
  • Kapan Anda punyawaktu untuk bertemu dengan saya? When do you have time to meet with me?

Differences between ‘Ketika’ and ‘Waktu’

1.  ‘Ketika’ is used in a formal situation while ‘Waktu’ is used in an informal situation.
2.  ‘Ketika’ and ‘Waktu’ are used as ‘when’ for an event or a state of affairs in the past. However, it is common to use ‘Waktu’ as ‘When’ when referring to  the future.
3.  ‘Ketika’ is used to indicate a hypothetical state. For example,

Ketika cinta harus memilih. When you have to choose between loves and …

Let’s practice ‘Kapan’, ‘Ketika’, and ‘Waktu’

1. __________________ Anda pergi ke Indonesia? [When will you go to Indonesia?]
2. __________________ saya kembali ke AS, saya akan melamar Maria. [When I return to the US, I will propose to Maria.]
3. __________________ saya sakit, Ibu saya merawat saya setiap hari. [When I was sick, my mother took care of me every day.]
4. __________________ itu saya belum bisa menyetir mobil. [At that time, I could not drive a car.]
5. Saya tidak tahu _____________ dia pulang.[I don’t know when he is going home.]
6. Tolong hubungi saya kalau Anda punya _____________. [Please call me when you have some time or available.]

Answer Key

1. Kapan
2. Waktu
3. Ketika/waktu
4. Waktu
5. Kapan
6. Waktu