Time difference between London and Sydney

The gap is not the same all year

Every converter gives one number for this pair. That number is right for most of the year and wrong for part of it, because London goes forward on the last Sunday in March and back on the last Sunday in October and Sydney goes forward on the first Sunday in October and back on the first Sunday in April.

These two are in opposite hemispheres, so their summers do not overlap: London is on summer time roughly when Sydney is not. The gap does not wobble by an hour around a settled figure — it swings between 9 hours and 11 hours and spends a good part of the year at each. There is no single right answer to give a calendar, which is why a recurring meeting between them is worth setting in one city's local time and letting the other side see it move.

About London and Sydney

London is the reference the rest of the system is measured from: Greenwich sits inside the city, and UTC±0 is its winter time. It does not stay there — Britain moves to UTC+1 for seven months of the year, which is why "London is GMT" is wrong more often than it is right.

Sydney is UTC+10 in winter and UTC+11 from October to April. Its summer is the northern hemisphere's winter, so the gap to Europe and North America swings by two hours over the year rather than staying put.

What 9 hours actually costs you

There is no shared working hour at all. Nine to five in London is 6:00 PM to 2:00 AM in Sydney. Somebody has to be outside their working day, and the only question is who — so the useful thing is to decide that once rather than rediscover it every time.

The least painful slot is 8:00 AM in London, which is 5:00 PM in Sydney. That is an hour outside somebody's working day and it is the smallest that gap gets — every other hour of the clock costs more.

At 9 hours the two are far enough apart that the date stops matching. Midday in London is 9:00 PM the same day in Sydney, but the ends of the working day do cross. "Tomorrow morning" means different things to the two of you, and a deadline given without a date attached will be missed by one side or the other.

When they can both be at their desks

Nine-to-five in London and nine-to-five in Sydney do not overlap at all. With 9 hours between them, one side is always outside working hours, and the practical question is which side takes the early start or the late finish rather than when to meet.

London

Sydney

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How far apart London and Sydney are

The shortest path over the Earth's surface between the two is 16,994 km (10,560 miles). That is beyond the range of almost every airliner in service, so in practice this journey is made with at least one stop, and the time in the air alone comes to around 21 hours.

Over that distance you cross 9 hours of clock, which is where jet lag comes from: the body shifts by about an hour a day, so 9 hours takes most people 9 days or so to absorb. Flying east to Sydney is the harder direction — you lose the hours and have to fall asleep earlier than your body wants.

London to Sydney, hour by hour

On the usual gap of 9 hours.

Frequently asked questions