Sydney to London time difference
Sydney is between 9 and 11 hours ahead of London, depending on which side of daylight saving each city is on. Most of the year, the gap sits at either 9 or 11 hours; the "neat" 10-hour difference only shows up briefly twice a year. Here's how to read it correctly, and how to pick a meeting time that doesn't ruin anyone's evening.
Why the time difference changes
Both cities observe daylight saving time, but on opposite calendars because they sit in opposite hemispheres. London uses British Summer Time (BST, UTC+1) from the last Sunday of March to the last Sunday of October. Sydney uses Australian Eastern Daylight Time (AEDT, UTC+11) from the first Sunday of October to the first Sunday of April. The rest of the year each city falls back to its standard time: GMT (UTC+0) for London and AEST (UTC+10) for Sydney.
Because the two countries shift in opposite directions, the gap between Sydney and London expands and contracts twice a year:
| Period (approx.) | London | Sydney | Difference |
|---|---|---|---|
| Late Oct – late Mar | GMT (UTC+0) | AEDT (UTC+11) | 11 hours |
| Late Mar – early Apr | BST (UTC+1) | AEDT (UTC+11) | 10 hours |
| Early Apr – early Oct | BST (UTC+1) | AEST (UTC+10) | 9 hours |
| Early Oct – late Oct | GMT (UTC+0) | AEDT (UTC+11) | 11 hours |
For the calmer months (April–September Northern summer), Sydney is just 9 hours ahead of London, which is the most generous gap for collaboration. During December and January, when London is dark and Sydney is on the beach, the gap stretches to 11 hours and live conversation becomes much harder.
Best meeting times between Sydney and London
With a 9- to 11-hour offset and Sydney ahead, the practical overlap between a normal working day in each city is short. Plan for one of two windows:
- Sydney morning ↔ London late evening: 8:00–10:00 in Sydney equals 22:00–00:00 in London during the wide gap, and 21:00–23:00 during the narrow gap. Workable for important calls but late for the London side.
- Sydney late afternoon/early evening ↔ London morning: 17:00–19:00 in Sydney equals 06:00–10:00 in London depending on DST. This is usually the best window: London starts the day, Sydney winds down.
Common meeting times at a glance
These rows assume the wide-gap period (London on GMT, Sydney on AEDT, 11 hours apart). Subtract one or two hours during DST overlaps.
| Sydney (AEDT) | London (GMT) | Verdict |
|---|---|---|
| 07:00 | 20:00 (prev. day) | Late dinner in London |
| 09:00 | 22:00 (prev. day) | Sydney happy, London asleep |
| 17:00 | 06:00 | Edge of London morning |
| 19:00 | 08:00 | Best mutual window |
| 21:00 | 10:00 | Late for Sydney, mid-morning London |
Notes for travellers and developers
If you are flying between the two, expect to lose roughly a calendar day on the
Sydney–London leg and gain it back on the return. For software teams,
always store timestamps in UTC: London oscillates between UTC+0 and UTC+1, and
Sydney between UTC+10 and UTC+11, so a single offset will eventually be wrong.
Convert to local time only at display time using the IANA zones
Europe/London and Australia/Sydney.
FAQ
Is Sydney always 11 hours ahead of London?
No. The difference varies between 9 and 11 hours. It is 11 hours only when London is on GMT and Sydney is on AEDT — roughly late October through late March.
What is the smallest time difference between Sydney and London?
9 hours, during the Northern Hemisphere summer when London is on BST and Sydney is on AEST.
What's the best time for a video call?
London 08:00–10:00 (= Sydney late afternoon/evening) is the most reliable overlap year-round.