What even is this? The Earth is divided into time zones based on how far east or west you are from a reference line called UTC. Every place has an offset, like +10 or −5, that tells you how many hours ahead or behind UTC it is. Converting between time zones is just adding or subtracting that difference.
1. UTC, The World's Reference Clock
UTC (Coordinated Universal Time) is the world's reference time. It doesn't change for daylight saving. Every time zone is defined as an offset from UTC, written as UTC+ (ahead) or UTC− (behind).
Think of UTC as the clock at the centre of the world. If you're in Australia, you're ahead of UTC, so you add hours. If you're in the USA, you're behind UTC, so you subtract hours.
The One Rule to Remember
⬆️ East
Add hours
Higher UTC offset = further east = later time
⬇️ West
Subtract hours
Lower UTC offset = further west = earlier time
2. Time Zones You Need to Know
| City / Region | Standard offset | Notes |
|---|---|---|
| Brisbane / QLD | UTC+10 | AEST, no daylight saving |
| Sydney / Melbourne | UTC+10 / UTC+11 | AEST in winter, AEDT (daylight saving) in summer |
| Adelaide | UTC+9:30 | ACST, half-hour offset! |
| Perth | UTC+8 | AWST, 2 hours behind Brisbane |
| Tokyo | UTC+9 | Japan Standard Time, no daylight saving |
| Dubai | UTC+4 | Gulf Standard Time |
| London | UTC+0 | GMT in winter, BST (UTC+1) in summer |
| New York | UTC−5 | EST in winter, EDT (UTC−4) in summer |
| Los Angeles | UTC−8 | PST in winter, PDT (UTC−7) in summer |
3. Converting Between Time Zones
There are two types of questions: comparing cities (what time is it there right now?) and flight calculations (what time do I land?). Both use the same steps.
1
Write down both UTC offsets. You need to know where each city sits on the number line.
2
Find the difference. Subtract the smaller offset from the larger:
difference = bigger offset − smaller offset3
Add or subtract. Going east? Add the difference. Going west? Subtract the difference. Use the original time as your starting point.
4
For flight times: Add the flight duration before converting to local time. Convert to UTC first, add flight time, then convert to destination time.
⚠️ Daylight Saving Trap: In exam questions, the time zone offset will usually be stated in the question. Always use the offset you're given, don't assume Sydney is always UTC+10, because in summer it becomes UTC+11 (AEDT). Brisbane stays at UTC+10 all year.
4. Worked Examples
Example A · Comparing Cities
It is 18:00 in Brisbane (UTC+10). What time is it in London (UTC+0)?
Step 1: UTC offsets, Brisbane
+10, London +0Step 2: Difference =
10 − 0 = 10 hoursStep 3: London is west of Brisbane, so subtract:
18:00 − 10 = 08:00✅ It is 08:00 in London when it's 18:00 in Brisbane.
Example B · Flight Arrival Time
A flight departs Brisbane (UTC+10) at 14:00. The flight is 9 hours. What is the local arrival time in Tokyo (UTC+9)?
Step 1: Convert departure to UTC. Brisbane is UTC+10, so:
14:00 − 10 = 04:00 UTCStep 2: Add flight duration:
04:00 + 9 hours = 13:00 UTCStep 3: Convert to Tokyo local time (UTC+9):
13:00 + 9 = 22:00✅ The plane lands at 22:00 Tokyo time.
Example C · Reading it Backwards
It is 07:00 in New York (UTC−5). What time is it in Brisbane (UTC+10)?
Step 1: UTC offsets, New York
−5, Brisbane +10Step 2: Difference =
10 − (−5) = 15 hoursStep 3: Brisbane is east of New York, so add:
07:00 + 15 = 22:00✅ It is 22:00 in Brisbane when it's 07:00 in New York.
Practice Questions
Q1 It is 10:00 in London (UTC+0). What time is it in Tokyo (UTC+9)?
Tap to reveal
19:00 Tokyo time.
Tokyo is east of London: 10:00 + 9 = 19:00. Tokyo is 9 hours ahead.
Tokyo is east of London: 10:00 + 9 = 19:00. Tokyo is 9 hours ahead.
Q2 A flight departs London (UTC+0) at 06:00 and takes 6 hours. It lands in Dubai (UTC+4). What is the local arrival time in Dubai?
Tap to reveal
16:00 Dubai time.
Departure: 06:00 UTC (London = UTC+0, so no conversion needed).
+ 6 hours flight = 12:00 UTC.
Convert to Dubai (UTC+4): 12:00 + 4 = 16:00.
Departure: 06:00 UTC (London = UTC+0, so no conversion needed).
+ 6 hours flight = 12:00 UTC.
Convert to Dubai (UTC+4): 12:00 + 4 = 16:00.
Q3 It is 07:00 in New York (UTC−5). What time is it in Brisbane (UTC+10)?
Tap to reveal
22:00 in Brisbane.
Difference: 10 − (−5) = 15 hours. Brisbane is east, so add: 07:00 + 15 = 22:00.
Difference: 10 − (−5) = 15 hours. Brisbane is east, so add: 07:00 + 15 = 22:00.
Q4 Sydney is on AEDT (UTC+11) during summer. Perth is UTC+8. If it's 20:00 in Sydney, what time is it in Perth?
Tap to reveal
17:00 in Perth.
Perth is west of Sydney. Difference: 11 − 8 = 3 hours. Subtract: 20:00 − 3 = 17:00.
Even though both are in Australia, daylight saving makes the gap 3 hours in summer.
Perth is west of Sydney. Difference: 11 − 8 = 3 hours. Subtract: 20:00 − 3 = 17:00.
Even though both are in Australia, daylight saving makes the gap 3 hours in summer.
Q5 A flight departs Brisbane (UTC+10) at 14:00 and lands in Los Angeles (UTC−8) after 13 hours. What local time does it arrive in LA?
Tap to reveal
09:00 LA time.
Step 1 · convert departure to UTC: 14:00 − 10 = 04:00 UTC.
Step 2 · add flight duration: 04:00 + 13 = 17:00 UTC.
Step 3 · convert to LA (UTC−8): 17:00 − 8 = 09:00.
Note: LA is 18 hours behind Brisbane. Even though you flew for 13 hours, you "arrive" in LA's morning, the clocks don't match the flight time because you crossed many time zones heading east-to-west across the Pacific.
Step 1 · convert departure to UTC: 14:00 − 10 = 04:00 UTC.
Step 2 · add flight duration: 04:00 + 13 = 17:00 UTC.
Step 3 · convert to LA (UTC−8): 17:00 − 8 = 09:00.
Note: LA is 18 hours behind Brisbane. Even though you flew for 13 hours, you "arrive" in LA's morning, the clocks don't match the flight time because you crossed many time zones heading east-to-west across the Pacific.
✈️ Escape Room
The World Clock
Josh is tracking six international flights for his school trip. Every clock is wrong and the departure board is frozen. Solve the time zone challenges before the gates close.
Start Escape Room →