Blois is on the main Paris–Tours–Bordeaux rail line. Direct trains from Paris Austerlitz take about 1h 30m and run hourly; the TER (regional service) is the standard option, with a few faster Intercités runs. From Tours, trains take 30–40 minutes; from Orléans, about 35 minutes.
The Gare de Blois is a flat 10-minute walk down Avenue Jean-Laigret to the château. The nearest major airports are Paris Orly (about 2 hours by car or train+RER) and Tours-Val de Loire (about 50 minutes by car), the latter served by a handful of European low-cost routes.
There is no direct international air access. Most visitors arrive by train from Paris, by car along the A10 autoroute (exit 17), or as part of a wider Loire Valley driving tour.