Sydney to London Time —
The Real Scheduling Guide
This pair breaks people because the seasons fight each other.
The gap in plain language
Sydney runs on Australian Eastern Time (AEST/AEDT). London runs on GMT/BST. Both observe daylight saving time — but they're in opposite hemispheres. When one is going into summer time, the other is heading into winter.
That creates three different realities each year:
- Northern winter / Southern summer (roughly Nov–Mar): Sydney is 11 hours ahead.
- Northern summer / Southern winter (roughly Apr–Oct): Sydney is 9 hours ahead.
- Two short transition windows (March/April and October/November): 10 hours difference.
The gap doesn't just change. It changes in opposite directions at roughly the same time. Nobody remembers which version they're in.
The honest overlap window
Assume working hours of 9am–6pm in both cities. Here's what actually overlaps — broken out by the three seasonal phases:
UK winter / AU summer (11-hour gap):
| 🇦🇺 Sydney | 🇬🇧 London |
|---|---|
| 9:00am – 10:00am ✦ | 8:00pm – 9:00pm ✦ |
| 10:00am – 6:00pm | 9:00pm – 5:00am |
In the 11-hour phase there is one semi-usable hour: 9–10am London / 8–9pm Sydney — at the edge of Sydney's evening.
UK summer / AU winter (9-hour gap):
The least painful window becomes 9–11am London / 6–8pm Sydney — two workable hours, but still pushing Sydney into evening.
Transition windows (10-hour gap):
For several weeks in March/April and October/November, the gap sits at 10 hours. The overlap is roughly one hour: 9–10am London / 7–8pm Sydney.
Outside these windows, one side is definitively outside working hours. The table is complete — and it is not encouraging.
The fairness problem
If London schedules at 4pm, Sydney joins at 1am (in the 9-hour phase) or 3am (in the 11-hour phase). That is not negotiation territory. So the cost almost always lands in Australia's evening.
A 9am London call is 8pm Sydney during the 11-hour period and 6pm Sydney during the 9-hour period. For UK-headquartered firms with APAC expansion, that means Sydney teams regularly end their day in meetings. Over time, that erodes energy — especially when it becomes daily or weekly.
This isn't a balanced time axis. It's structurally skewed toward UK mornings and Australian evenings. The only way to make it fair is to rotate explicitly — and to treat that rotation as a policy, not an afterthought.
The DST trap
This is where it gets genuinely complicated. The UK switches in late March and late October. New South Wales (Sydney) switches in early October and early April.
Because they move on different dates and in opposite seasonal directions, the gap passes through 10 hours twice a year for several weeks. That means a recurring 9am London meeting might be 8pm Sydney one month, 7pm the next, 6pm the month after that.
Standing invites don't track this nuance. People show up at the wrong time — or worse, they don't realise the time has become materially worse for one side without anyone explicitly deciding that.
If you manage UK–Australia coordination, you need a DST calendar — not just a static time difference. Audit every recurring meeting in March and October.