Sydney Airport has direct rail, taxi, rideshare, bus and transfer options. The best choice depends on your terminal, group size, luggage and final address.
Train
Airport rail is a predictable way to avoid road congestion for many central destinations.
Taxi and rideshare
Road transport can be easier with several travelers or heavy luggage, but compare live traffic.
Terminal matters
T1 is international while T2/T3 are domestic; make sure you are following transport signs for the terminal where you actually arrive.
International and domestic terminals are separate precincts
Sydney T1 is international while T2 and T3 are domestic, and the airport says you cannot simply walk between the two precincts. That matters if your city trip starts after a domestic connection or if you are meeting someone in another terminal. Check the exact terminal before choosing train, taxi or rideshare pickup instructions.
Sources and verification
Time-sensitive airport, airline, visa, security and transport details should always be confirmed with the relevant official source before travel.