Fredrikstad is 90 km south of Oslo and easily reached by train. NSB/Vy trains run from Oslo S (Oslo Central Station) to Fredrikstad station roughly every hour; the journey takes around 1 hour. The station sits on the east bank of the Glomma in the New Town, a short walk from the passenger ferry to Gamlebyen.
By car, take the E6 motorway south from Oslo, then the E18 towards Fredrikstad. Parking in the town centre can be tight in summer. Buses also run from Oslo Bus Terminal (Galleri Oslo), though the train is faster and more comfortable. There is no direct airport in Fredrikstad; most visitors fly into Oslo Gardermoen and continue by train.