London vs Sydney Time Difference

City Comparison

Sydney is 9, 10 or 11 hours ahead of London — and which of the three applies depends on the date. Almost every other major city pair has one summer figure and one winter figure. This one has three, because London and Sydney are in opposite hemispheres and move their clocks in opposite directions at different times of year. Get the wrong number and your call lands in the middle of somebody’s night.

The Three Different Time Differences

Two clock changes on each side, four transitions a year, and none of them fall on the same weekend. The result is a difference that steps between three values:

The two 10-hour windows are the dangerous ones, because they are short and nobody expects them. In 2026 the spring window lasts exactly seven days, from 29 March to 5 April, and the autumn window lasts three weeks, from 4 October to 25 October. A standing weekly call booked as a fixed local time on one side will drift by an hour on the other, twice inside a month.

Compare the live clocks on the London and Sydney pages to see which of the three figures currently applies. The dates themselves are set out in When Do the Clocks Change? DST Dates Around the World.

Why the Gap Moves Twice as Much as Usual

On a normal transcontinental pair — London and New York, say — both cities change their clocks in the same direction within a few weeks of each other, so the difference is stable for most of the year and wobbles by an hour for a fortnight. London and Sydney do the opposite:

• Late March. London springs forward to British Summer Time, so it moves towards Sydney and the gap narrows from 11 to 10.
• Early April. Sydney ends its daylight saving and falls back, moving away from London. The gap narrows again, to 9.
• Early October. Sydney springs forward into AEDT while London is still on BST. The gap widens to 10.
• Late October. London falls back to GMT. The gap widens to 11, where it stays until spring.

Because the two hemispheres have opposite summers, the changes never cancel each other out — they add up. Across the year the difference swings by a full two hours, the largest annual swing of any major city pair on this site. The rules on each side are covered in Time Zones in the United Kingdom Explained and Time Zones in Australia Explained.

Hour by Hour, in Both Seasons

Below is the same London day converted twice: once at the narrow 9-hour gap of the northern summer, once at the wide 11-hour gap of the northern winter.

Two things fall out of that table. First, a conventional London working day of 09:00 to 17:00 covers 18:00 to 02:00 in Sydney at best and 20:00 to 04:00 at worst — there is no honest overlap with Australian office hours after the first hour. Second, the calendar date in Sydney rolls over in the middle of the London afternoon, so for half of every London working day the two cities are on different dates. Write the date into every invitation, not just the time.

The Best Time to Call

There is exactly one band that works without asking anyone to get up before dawn: the early London morning, which is the end of the Sydney working day.

• 07:00 London = 16:00 or 18:00 Sydney. The best single slot in the year, in both seasons. Sydney is still at the desk; London is early but civilised.
• 08:00 London = 17:00 or 19:00 Sydney. Fine in the northern summer, late in the northern winter — acceptable occasionally, not as a weekly fixture.
• 09:00 London = 18:00 or 20:00 Sydney. The northern-summer version still works; the northern-winter version is an evening intrusion and should be avoided for anything routine.

Going the other way is worse. A Sydney morning of 09:00 is midnight or 22:00 the previous evening in London, which is why Australian teams almost always absorb the late slot rather than British teams taking the early one. If the relationship is long-term, alternate: London takes 07:00 one month, Sydney takes 19:00 the next. The full European version of this problem, including Perth and the other Australian zones, is in Best Time for Meetings Between Europe and Australia, and the structural answer — stop trying to meet at all and hand work over instead — is in How to Run a Follow-the-Sun Team.

If your Australian counterpart is in Perth rather than Sydney, the arithmetic gets considerably kinder: Western Australia stays on UTC+8 all year and never changes its clocks, putting it 7 or 8 hours ahead of London instead of 9 to 11. Brisbane also skips daylight saving, so it holds a steady UTC+10 and sits an hour behind Sydney for five months of the year.

The Two Stock Exchanges Never Meet

The Australian Securities Exchange trades from 10:00 to 16:00 Sydney time. The London Stock Exchange trades from 08:00 to 16:30. Convert both to a single reference and the result is a clean miss:

Sydney closes before London opens, every single day, in every season. That is why the ASX reacts to the previous New York close rather than to anything happening in Europe, and why London traders arrive to a fully settled Australian session. The only pair on this site with a similar clean separation is London and Tokyo, where the Tokyo close and the London open are also separated by roughly an hour.

Flying Between Them: Two Days Out, One Day Back

London to Sydney is about 17,000 km in a straight line — the classic Kangaroo Route, normally flown with one stop in Singapore, Dubai, Doha or Hong Kong for a total journey of roughly 22 to 24 hours. The clock arithmetic is lopsided in a way that catches people out:

Both examples cover the same elapsed time. Heading east you are flying against the clock, adding 11 hours of offset on top of a day in the air, so the itinerary shows a +2. Heading west you are flying with the clock, subtracting 11 hours, so a 24-hour journey lands on the next morning. The method for reading these itineraries is in Understanding Flight Times Across Time Zones.

A point that surprises most travellers: this route never crosses the International Date Line. The Kangaroo Route runs east from Europe across Asia, so you accumulate the whole 9 to 11 hours by moving through ordinary time zones. There is no skipped date and no repeated date — the “+2” on the ticket is pure elapsed time plus offset. Contrast this with Sydney to Los Angeles, which does cross the line and can land hours before it departed; see Crossing the International Date Line.

For jet lag, the eastbound leg is the harder one. London to Sydney compresses the body clock by 9 to 11 hours in the direction it least likes, and most travellers need eight to eleven days to settle. The return, a westward shift of the same size, usually resolves in five or six. The reason for the asymmetry is explained in Why Flying East Causes Worse Jet Lag Than Flying West.

New Year, Sport and the Half-Day Head Start

Sydney reaches midnight on 31 December 11 hours before London, so the harbour fireworks are a lunchtime broadcast in Britain — 13:00 GMT on New Year’s Eve. In the other direction, an evening kick-off in Sydney at 19:30 AEDT is 08:30 in London, which is why Ashes cricket and Australian rugby fixtures are a breakfast fixture for British audiences rather than a late-night one.

The same head start applies to anything with a deadline. If a contract is due “by end of day Friday” and the parties are in London and Melbourne, the Australian end of day passed before the British working day began. Write “17:00 London time on Friday 10 April”, not “end of day Friday”, and state the zone in the form “AEDT (UTC+11)” rather than bare letters — the reasons are set out in Time Zone Abbreviations Explained.

Frequently Asked Questions

How many hours ahead is Sydney of London?

Between 9 and 11 hours, depending on the month. It is 9 hours from early April to early October, 11 hours from late October to late March, and 10 hours during two short crossover periods — roughly one week at the end of March and three weeks in October.

Why does the London to Sydney time difference change three times a year?

Because both cities observe daylight saving time but in opposite hemispheres, so their clock changes fall at four different points in the year. Britain moves on the last Sundays of March and October; New South Wales moves on the first Sunday of October and the first Sunday of April. Between each pair of changes the difference sits at an intermediate value.

When it is 9:00 AM in London, what time is it in Sydney?

18:00 the same evening during the northern summer, or 20:00 during the northern winter. In both cases the Australian working day has already finished, which is why 07:00 in London is a far better slot for a shared call.

Is Sydney a day ahead of London?

For part of every day, yes. Sydney crosses midnight when London reaches 13:00 in the northern winter or 15:00 in the northern summer, so for the second half of the London working day the Australian calendar has already moved on to the next date.

Does a flight from London to Sydney cross the International Date Line?

No. The usual routing goes east across Asia, so the entire offset is accumulated through ordinary time zones. The two-day itinerary is caused by 22 to 24 hours of travel added to a 9 to 11 hour offset, not by a date-line crossing. Only trans-Pacific routings, such as Sydney to Los Angeles, cross the line.

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Related guides

• Best Time for Meetings Between Europe and Australia
• Time Zones in Australia Explained
• Time Zones in the United Kingdom Explained
• When Do the Clocks Change? DST Dates Around the World
• How to Run a Follow-the-Sun Team
• Crossing the International Date Line
• Understanding Flight Times Across Time Zones
• Why Flying East Causes Worse Jet Lag Than Flying West
• London vs Tokyo Time Difference
• Time Zone Abbreviations Explained: EST, EDT, CET and IST