London and Sydney: when you are both awake
You never get an evening together. You do get 8h a day, and the shape of it moves 4 times a year.
The short version
These two never get an evening together. Whatever hour you pick, one of you is starting the day and the other is ending it, and no amount of rearranging changes that. What does change is the shape: from April, Sydney gives up an hour and London takes one, so the late-night window that was three hours long in January becomes one. Couples who settle into a 21:00 London call in February find it has quietly stopped working by May.
The window that works all year
Most of these windows stop working when the clocks change. This one does not: it is inside every one of the 5 periods below, so a standing time set here survives the whole of 2026.
07:00 in London · 5h wide
Only the London time is fixed. On Sydney’s clock the same moment falls between 16:00 and 18:00, depending on which period of the year it is. Set the alarm in London.
Every period in 2026
The gap between London and Sydney is not one number. It holds still for a while, then moves, 4 times a year, because the two cities change their clocks on different dates.
| Period | Gap | Both awake | Shared evening |
|---|---|---|---|
| 2026-01-01 → 2026-03-29 | +11h | London 07:00–12:00 = Sydney 18:00–23:00 · 5h London 20:00–23:00 = Sydney 07:00–10:00 (next day) · 3h | never |
| 2026-03-29 → 2026-04-04 | +10h | London 07:00–13:00 = Sydney 17:00–23:00 · 6h London 21:00–23:00 = Sydney 07:00–09:00 (next day) · 2h | never |
| 2026-04-04 → 2026-10-03 Now | +9h | London 07:00–14:00 = Sydney 16:00–23:00 · 7h London 22:00–23:00 = Sydney 07:00–08:00 (next day) · 1h | never |
| 2026-10-03 → 2026-10-25 | +10h | London 07:00–13:00 = Sydney 17:00–23:00 · 6h London 21:00–23:00 = Sydney 07:00–09:00 (next day) · 2h | never |
| 2026-10-25 → 2027-01-01 | +11h | London 07:00–12:00 = Sydney 18:00–23:00 · 5h London 20:00–23:00 = Sydney 07:00–10:00 (next day) · 3h | never |
“Both awake” counts hours between 07:00 and 23:00 in each city, the same window Clockin Duo uses to decide whether to show a partner as asleep.
Before you start
How many hours do London and Sydney share?
Do London and Sydney ever share an evening?
Does the time difference between London and Sydney change during the year?
Which cities this covers
Times are for London (Europe/London) and Sydney (Australia/Sydney). Anywhere sharing those zones gets the same answer, so this also covers Manchester, Edinburgh, Dublin, Lisbon on one side and Melbourne, Canberra, Hobart on the other.