German Railways (DB) operates a train from Regensburg to Karlovy Vary hourly. Tickets cost $35 - $55 and the journey takes 1 h 33 min. 2 other operators also service this route. Alternatively, FlixBus operates a bus from Regensburg to Karlovy Vary twice daily. Tickets cost $9 - $17 and the journey takes 2 h 5 min. 4 other operators also service this route.
From Regensburg Hbf train to Marktredwitz, train to Cheb, then train to Karlovy Vary. 3 h 55 min 42€. From Regensburg, Regensburg central station bus to Pilsen, bus to Loket, then bus to Karlovy Vary - Pivovar. 5 h 55 min 18€. From Regensburg drive to Karlovy Vary. 1 h 46 min 23€.