Callander lost its railway station in 1965 — one of Beeching's less-lamented closures — and is now reached by road or bus. The A84 from Stirling is the main approach, about 26 km, and takes around 30 minutes. From Glasgow the journey is around an hour via the M9 and A84. Edinburgh is about 1 hour 15 minutes via the M9.
By bus: First Scotland operates services from Stirling bus station (route 59 and related services), with connections to Glasgow and Edinburgh at Stirling. The journey from Stirling takes around 45 minutes. There is also a seasonal Trossachs Trundler bus that connects Callander with Aberfoyle and other Trossachs destinations between April and October — useful for circular walking routes.
Nearest airports: Edinburgh Airport (about 1 hour) and Glasgow Airport (about 1 hour 15 minutes) are the main options. Glasgow Prestwick is further away. A hire car or taxi from either airport makes the most sense; public transport connections require going via the respective city centre.