How far and how long
Budapest to central Vienna is 240 km via the M1 motorway. Expect 2h30–3h door to door depending on traffic at the Austrian border and inside Vienna.
Transfer vs. train vs. flight
Railjet trains (Budapest Keleti → Wien Hbf) take about 2h40 and are frequent. Flights are technically available but make no sense once you factor in airport time. Private transfers win when you have luggage, multiple stops, or need to arrive outside train schedules.
Border crossing
Hungary and Austria are both in the Schengen area — no passport control for EU citizens, and travellers from most third countries pass through without scheduled stops.
