Sydney Airport is about 8km south of the city centre and is easily accessible by train from Central Station. The airport is split into domestic and international terminals that are several kilometres apart. The international terminal is all contained in one building, while the domestic terminal is comprised of separate buildings that are used for Jetstar, Qantas, Rex and Virgin Australia flights.
The easiest way to the airport is the new Airport train line that whisks you to the airport in around ten minutes. Trains leave from Central Station and less frequently from other stations on the City Circle line. The one-way fare from the Domestic Terminal to Central Station or Kings Cross is $16.40; one-way fares from the International Terminal are $17.20 to Kings Cross or any station in the city centre.
The train fare between the two terminals costs $5.40, but there are also free buses linking the domestic and international terminals.