Chantilly is about 40 kilometres north of Paris and one of the easiest day trips in the Île-de-France.
By train, take the TER from Paris Gare du Nord toward Creil. Trains run roughly every half hour and take 25 minutes to reach Chantilly–Gouvieux station. The walk from the station to the château gates takes 25 minutes through the town and across the park; alternatively the Domaine Express shuttle bus runs from the station to the château on weekends and holidays.
By car, take the A1 motorway north from Paris (about 35 minutes outside rush hour) and follow signs to Chantilly. Parking is plentiful next to the château grounds. Charging stations are available at the main car park.
By RER + connection, the RER D to Creil and a short backtrack to Chantilly is possible but less convenient than the direct train from Gare du Nord.