Coaching Centre
Australian time zones and daylight saving
Australia's three standard time zones, which states use daylight saving and when, the odd ones out such as Broken Hill and Lord Howe Island, and problems that cross zones.
Australia is wide enough to span about $40°$ of longitude, which is roughly $2\tfrac12$ hours of sun time. On top of that, some states move their clocks in summer and some don't. In January there are five different mainland times at once. This section sorts them out.
Three standard zones
| Zone | Offset | Who uses it |
|---|---|---|
| Australian Eastern Standard Time (AEST) | UTC+10 | Queensland, NSW, ACT, Victoria, Tasmania |
| Australian Central Standard Time (ACST) | UTC+9:30 | South Australia, Northern Territory, Broken Hill (NSW) |
| Australian Western Standard Time (AWST) | UTC+8 | Western Australia |
Broken Hill is in NSW but runs on South Australian time. Its rail and business links have always been with Adelaide. Lord Howe Island, $600$ km off the NSW coast, uses UTC+10:30. And a few roadhouses near Eucla on the Nullarbor unofficially keep UTC+8:45, so drivers crossing the border change their watches by $45$ minutes.
Daylight saving
In summer, NSW, the ACT, Victoria, Tasmania and South Australia move their clocks forward one hour. This gives an extra hour of daylight in the evening. Queensland, the Northern Territory and Western Australia stay on standard time all year. Queensland voted against it in a 1992 referendum, and WA voted it down in 2009 after a three-year trial.
- Starts: 2:00 am on the first Sunday in October. Clocks jump to 3:00 am, so that night is an hour shorter.
- Ends: 3:00 am on the first Sunday in April. Clocks go back to 2:00 am, so that night is an hour longer.
During daylight saving the eastern states are on AEDT (UTC+11) and South Australia is on ACDT (UTC+10:30). Lord Howe Island only moves its clocks by half an hour, to UTC+11.
- Choose July. Set Sydney to $09{:}00$. Which cities show $08{:}30$? Which shows $07{:}00$?
- Switch to January with Sydney still at $09{:}00$. Which cities change, and which stay the same?
- Set the clock in Perth at $18{:}00$ in January. What time is it in Hobart? Is it the same day?
- Count the different colours on the mainland in January and in July.
Working across zones
It is $9{:}00$ am in Sydney. Find the time in Perth, Adelaide and Brisbane (a) in July (b) in January.
In January, a flight leaves Perth at $6{:}10$ am and takes $4$ h $5$ min to reach Sydney. When does it land, in Sydney time?
Daylight saving starts in NSW on Sunday 4 October 2026. A security guard works from $10{:}00$ pm Saturday to $6{:}00$ am Sunday. How many hours does the guard actually work?
Your turn
In January, a plane leaves Darwin at $11{:}20$ pm on Tuesday and flies $4$ h $15$ min to Sydney. When does it land in Sydney?
Show the working
On Darwin's clock it lands at $11{:}20$ pm $+ 4$ h $15$ min $= 3{:}35$ am Wednesday. In January Darwin is on UTC+9:30 and Sydney is on UTC+11, so Sydney is $1$ h $30$ min ahead: $5{:}05$ am Wednesday.
Which of these does not use daylight saving?
Queensland, the Northern Territory and Western Australia stay on standard time all year.
In July it is $10{:}00$ am in Melbourne. What time is it in Adelaide?
In July Melbourne is on UTC+10 and Adelaide on UTC+9:30, so Adelaide is $30$ minutes behind.
In January, how many hours is Sydney ahead of Perth?
Sydney is on UTC+11 (daylight saving) and Perth on UTC+8: $11 - 8 = 3$ hours.
In July, how many hours is Sydney ahead of Perth?
UTC+10 and UTC+8: $10 - 8 = 2$ hours.
In January it is $6{:}00$ pm in Brisbane. What time is it in Sydney?
Brisbane stays on UTC+10 and Sydney is on UTC+11 in summer, so Sydney is one hour ahead.
Broken Hill, in New South Wales, keeps the same time as:
Broken Hill uses Central time, the same as South Australia.
In January, how many minutes is Adelaide behind Sydney?
Adelaide is on UTC+10:30 and Sydney on UTC+11 in January: a difference of $30$ minutes.
On the night daylight saving starts, a nurse works from $10{:}00$ pm to $6{:}00$ am by the clock. How many hours does the nurse actually work?
The clocks skip from 2:00 am to 3:00 am, so the usual $8$ hours becomes $7$.
Exam style: In January a flight leaves Perth at $6{:}10$ am and takes $4$ h $5$ min to reach Sydney. When does it land, Sydney time?
Perth time on landing: $10{:}15$ am. Sydney is $3$ hours ahead in January: $1{:}15$ pm.
Exam style: In January a flight leaves Darwin at $11{:}20$ pm Tuesday and takes $4$ h $15$ min to reach Sydney. When does it land, Sydney time?
Darwin time on landing: $3{:}35$ am Wednesday. Darwin is UTC+9:30 and Sydney is UTC+11 in January, a difference of $1$ h $30$ min. $3{:}35 + 1{:}30 = 5{:}05$ am Wednesday.