Business hours are most commonly 9:00 until 17:30, Monday to Friday, with a small variation either side. Places in the north of Australia sometimes open and close a little earlier. If trying to contact a business in another part of Australia, remember about time differences.
Government offices often close at 17:00, or even 16:30. Shops may stay open later, particularly on Thursday and Friday evenings, and most will be open on Saturdays, and some on Sundays.
The larger the town, the more likely shops are to indulge in extended trading hours. Corner shops will usually stay open until about 20:00, and some even later. Supermarkets in the big cities are often open 24 hours a day, and even in smaller towns they are likely to remain open until about 22:00 on weekdays.