London to Sydney is one of the most interesting time zone relationships in global business — not because the gap is the largest, but because it's constantly shifting. Depending on the time of year, the difference between the two cities ranges from 9 hours all the way to 11 hours. Both cities observe daylight saving time, but they do so in opposite seasons. When London springs forward, Sydney falls back — and vice versa. This creates a dynamic scheduling puzzle that rewards teams who plan ahead. Our time zone meeting planner handles all of this automatically so you don't have to track it manually.
Time Zone Overview: Four Seasons, Four Gaps
London alternates between GMT (UTC+0) from late October through late March and BST (UTC+1) from late March through late October. Sydney alternates between AEDT (UTC+11) from early October through early April and AEST (UTC+10) from early April through early October. Because they're in opposite hemispheres, their DST periods overlap for only a few months — and produce four distinct gap configurations.
| Period | London | Sydney | Time Difference |
|---|---|---|---|
| Northern summer (Apr–Sep) | BST (UTC+1) | AEST (UTC+10) | 9 hours — Sydney ahead |
| Southern summer (Oct–Mar, core) | GMT (UTC+0) | AEDT (UTC+11) | 11 hours — Sydney ahead |
| Both on DST (late Mar, brief Oct window) | BST (UTC+1) | AEDT (UTC+11) | 10 hours — Sydney ahead |
| Neither on DST (brief Apr, Oct window) | GMT (UTC+0) | AEST (UTC+10) | 10 hours — Sydney ahead |
The gap swings between 9 and 11 hours across the year, with brief 10-hour transition windows in spring and autumn when both hemispheres are either both on DST or both off it. This 2-hour range is significant — it means the same London morning meeting can land anywhere from Sydney's late afternoon to Sydney's evening depending on the season.
Finding the Overlap: The London Morning Window
The only truly workable overlap for London–Sydney is the London morning window, where London starts early and Sydney finishes late. Here's how it plays out across the seasons:
- Northern summer (9-hour gap): 7:00–9:00 AM London = 4:00–6:00 PM Sydney. This is the best season — Sydney finishes at a comfortable late afternoon hour.
- Southern summer (11-hour gap): 7:00–9:00 AM London = 6:00–8:00 PM Sydney. Still workable, but Sydney is pushing into evening territory.
- Transition periods (10-hour gap): 7:00–9:00 AM London = 5:00–7:00 PM Sydney. A comfortable middle ground.
The reverse window — Sydney morning to London evening — is theoretically possible but rarely used. A 9:00 AM Sydney start means a 10:00 PM London call during northern summer, or a midnight London call during southern summer. Most teams find the London morning / Sydney late afternoon arrangement far more practical.
Opposite-Season DST: The Scheduling Wildcard
The London–Sydney DST relationship is genuinely unique. Because the two cities are in opposite hemispheres, when one springs forward, the other falls back. This creates a twice-yearly period where the gap changes dramatically in a short time:
In late March / early April, London springs forward (GMT→BST) while Sydney falls back (AEDT→AEST). The gap compresses from 11 hours to 9 hours in a matter of weeks — a 2-hour swing. A recurring 7:00 AM London meeting that hits 6:00 PM Sydney in February suddenly lands at 4:00 PM Sydney by mid-April. That's the difference between "staying late" and "leaving on time."
In October, the reverse happens. Sydney springs forward (AEST→AEDT) while London falls back (BST→GMT). The gap expands from 9 hours to 11 hours. That 4:00 PM Sydney meeting suddenly becomes a 6:00 PM Sydney meeting — pushing your Australian colleagues from late afternoon into evening.
The practical implication: you cannot set a single recurring time and forget it. Either the time must shift with the seasons, or one side must accept that the meeting will land at different points in their workday depending on the time of year. Most teams choose to shift — scheduling earlier in London's winter to keep Sydney at a reasonable hour, and later in London's summer for the same reason.
Practical Tips for London–Sydney Teams
Own the seasonality. Don't pretend the gap is static. Review your recurring meeting schedule at each equinox and adjust times to maintain a reasonable window for both sides. A 15-minute calendar check twice a year saves months of resentment.
London owns the early start. The most sustainable pattern is London starting at 7:00–8:00 AM and Sydney finishing at 4:00–7:00 PM (depending on season). It's far easier for London to start an hour early than for Sydney to stay past 8:00 PM regularly.
Consider the "seasonal swap." During northern summer (when the gap is only 9 hours), you can push the meeting slightly later — say 9:00 AM London / 6:00 PM Sydney. During southern summer (11-hour gap), pull it earlier — 7:00 AM London / 6:00 PM Sydney. The Sydney side stays roughly constant while London flexes.
Coordinating between Europe and Australia? Find your seasonal sweet spot — Try the Time Zone Meeting Planner →