There are three Standard Time zones: Sumatra, Java and West & Central Kalimantan are 7 hours ahead of Greenwich Mean Time (GMT+7)
Bali, Nusa Tenggara, South & East Kalimantan and Sulawesi are 8 hours ahead of Greenwich Mean Time (GMT+8)
Irian Jaya and Maluku are 9 hours ahead of Greenwich Mean Time (GMT+9)