Los Angeles 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 17 hours ahead of Los Angeles. To arrive already keeping Sydney hours, your bedtime has to move 7 hours later — from 10:00 pm to 5:00 am, on your own clock at home. That is 7 nights, so the table below starts 7 nights before you fly.
| Night | Bed | Up | Moved | Sunset there on this clock | Sunrise there on this clock |
|---|---|---|---|---|---|
| Night 1 | 11:00 pm | 7:30 am | +1h | 12:50 am | 12:47 pm |
| Night 2 | 12:00 am | 8:30 am | +2h | 12:51 am | 12:45 pm |
| Night 3 | 1:00 am | 9:30 am | +3h | 12:51 am | 12:44 pm |
| Night 4 | 2:00 am | 10:30 am | +4h | 12:52 am | 12:43 pm |
| Night 5 | 3:00 am | 11:30 am | +5h | 12:53 am | 12:41 pm |
| Night 6 | 4:00 am | 12:30 pm | +6h | 12:53 am | 12:40 pm |
| Night 7 | 5:00 am | 1:30 pm | +7h | 12:54 am | 12:38 pm |
The gap, and why it is two numbers
In January, Sydney runs 19 hours ahead of Los Angeles. In July it runs 17 hours ahead. Both Los Angeles 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 5 hours later in January and 7 hours later in July. At the planner's usual step of an hour a night, that is 5 nights of shifting in January and 7 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.
Los Angeles to Sydney through the year
Los Angeles to Sydney crosses the date line, and the clock difference runs from seventeen to nineteen hours ahead, because the two cities change their clocks in opposite seasons. It is nineteen hours from the first Sunday of November to the second Sunday of March, and seventeen through the southern winter, from the first Sunday of April to the first Sunday of October. For the few weeks between the American and Australian changes, in March and in October, it is eighteen.
Seventeen to nineteen hours ahead is also five to seven hours behind, on a clock that has only twenty-four hours, and the planner takes the shorter way: five to seven hours later. By the sun, Sydney is about six hours behind Los Angeles going west over the Pacific, since it lies 91 degrees in that direction. The two cities are about 12,070 km apart on the great circle.
A 10:00 pm bedtime in Los Angeles is 5:00 pm the next day in Sydney in January, and 3:00 pm in July. Before you fly in January, bedtime moves an hour later each night for five nights, to 3:00 am on Los Angeles's clock, which is 10:00 pm in Sydney. After you land, the plan starts from 5:00 pm local time and moves an hour later each night until 10:00 pm on the fifth.
From 5:00 am in Los Angeles in January, and 7:00 am in July, Sydney is already on the next calendar day, so for most of the Los Angeles day the two cities are on different dates.
The date on the calendar jumps forward a day on the way out and back a day on the way home. Sydney's midsummer sunset, 8:09 pm on New Year's Day, is 1:09 am the same day in Los Angeles, and Los Angeles's latest sunset, 8:08 pm in late June, is 1:08 pm the next day in Sydney. A Los Angeles alarm at 6:30 am is 1:30 am the next day in Sydney in January, and 11:30 pm the same day in July. On the return the planner takes the move as five to seven hours earlier, over the same number of nights.
Going back
The return leg has its own page: Sydney to Los Angeles.
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.