London to Sydney
The clock moves whether or not you are ready for it. This works out by how much, and what a bedtime walked an hour a night would look like on the way there or once you arrive.
Sydney runs 9 hours ahead of London. To arrive already keeping Sydney hours, your bedtime has to move 9 hours earlier — from 10:00 pm to 1:00 pm, on your own clock at home. That is 9 nights, so the table below starts 9 nights before you fly.
| Night | Bed | Up | Moved | Sunset there on this clock | Sunrise there on this clock |
|---|---|---|---|---|---|
| Night 1 | 9:00 pm | 5:30 am | −1h | 8:49 am | 8:50 pm |
| Night 2 | 8:00 pm | 4:30 am | −2h | 8:49 am | 8:48 pm |
| Night 3 | 7:00 pm | 3:30 am | −3h | 8:50 am | 8:47 pm |
| Night 4 | 6:00 pm | 2:30 am | −4h | 8:51 am | 8:45 pm |
| Night 5 | 5:00 pm | 1:30 am | −5h | 8:51 am | 8:44 pm |
| Night 6 | 4:00 pm | 12:30 am | −6h | 8:52 am | 8:43 pm |
| Night 7 | 3:00 pm | 11:30 pm | −7h | 8:53 am | 8:41 pm |
| Night 8 | 2:00 pm | 10:30 pm | −8h | 8:53 am | 8:40 pm |
| Night 9 | 1:00 pm | 9:30 pm | −9h | 8:54 am | 8:38 pm |
The gap, and why it is two numbers
In January, Sydney runs 11 hours ahead of London. In July it runs 9 hours ahead. Both London and Sydney change their clocks, but not in step with each other, so a single figure would be wrong for months at a time. The planner above works from the difference on the date in its field.
What that asks of a bedtime
Taking the shorter way round the dial, the move is 11 hours earlier in January and 9 hours earlier in July. At the planner's usual step of an hour a night, that is 11 nights of shifting in January and 9 in July, either before you fly or after you land.
This is clock arithmetic and nothing else. It does not know how you sleep on aeroplanes, it makes no claim about how quickly anybody adjusts, and an hour a night is a step size rather than a finding. Shorten the step in the planner if a smaller one suits you.
London to Sydney through the year
London to Sydney has three different gaps across the year, because the two cities change their clocks in opposite seasons. From late October to the end of March, Sydney is on daylight saving time and London is not, and the gap is eleven hours. Through the southern winter, from the first Sunday of April to the first Sunday of October, it is nine. In the weeks between, when both cities are on summer time at once, it is ten: one week at the end of March and about three weeks in October.
By the sun Sydney is about ten hours ahead, since it lies 151 degrees further east. The two cities are about 16,990 km apart on the great circle.
Going east by nine to eleven hours, the planner takes the move as earlier rather than later, because that is the shorter way round the dial; past twelve hours it would turn round and go the other way. A 10:00 pm bedtime in London is 9:00 am the next morning in Sydney in January, and 7:00 am in July. At an hour a night, the move takes eleven nights in January and nine in July. Before you fly in July, the last night's bedtime is 1:00 pm on London's clock.
From 1:00 pm in London in January, it is already the next day in Sydney. Sydney's midsummer sunset, 8:09 pm on New Year's Day, is 9:09 am in London.
Sydney's latest sunrise, 7:09 am on 4 April in 2026, the last day before its clocks go back, is 9:09 pm the evening before in London. London's midwinter sunset, 3:51 pm in the middle of December, is 2:51 am the next day in Sydney. After you land in January, the plan starts from 9:00 am local time and comes back an hour a night to 10:00 pm, eleven nights later.
Going back
The return leg has its own page: Sydney to London.
Once you are there
With the clocks settled, the ordinary question comes back: what time to go to bed for the alarm you have set. That is the wake-time pages, which count in cycles rather than in zones.