Sydney time explained
Sydney observes daylight saving on a southern-hemisphere schedule, moving forward in early October and back in early April — the opposite way round to Europe and North America. That means the gap between Sydney and London swings by two hours across the year, which is the single most common cause of mis-scheduled calls between the two.
Sydney does observe daylight saving, so its offset from UTC changes twice a year. The time above already accounts for whichever is currently in force.
Reaching Sydney
A Sydney morning is the early morning across Asia and a Sydney afternoon is the European night, so the first half of the day is the only practical international window — and it narrows by an hour when southern daylight saving begins.
How this page works
The time above is calculated on your own device from the IANA time zone
database that ships with your browser, using the zone
Australia/Sydney. Nothing is fetched from a server, and the offset
shown is whatever is currently in force rather than a
number typed into the page — so when a country changes its rules, this
page changes with it.
The difference from your own clock is worked out the same way, comparing Sydney's current offset against your device's. If your computer's clock is wrong, so is that comparison.