Chinon sits about 45 km southwest of Tours. There is no direct train from Paris — you change at Tours. From Paris Montparnasse, catch a TGV to Tours (about 1 hour), then a regional train to Chinon (around 50 minutes). The total journey is roughly 2.5 to 3 hours. Trains from Tours to Chinon run several times a day; check the SNCF timetable as frequency is limited.
By car from Paris, take the A10 motorway towards Tours and then follow the D751 along the south bank of the Vienne. The drive takes about 3 hours.
Chinon is on the Loire à Vélo cycling route, which makes it accessible by bicycle from Tours or Saumur for those doing the trail. The route along the Vienne is particularly pleasant.