Great Western Railway operates a train from Portsmouth to Southampton hourly. Tickets cost $14 - $26 and the journey takes 41 min. South Western Railway also services this route hourly. Alternatively, National Express operates a bus from Portsmouth to Southampton every 3 hours. Tickets cost $6 - $10 and the journey takes 45 min. First also services this route every 30 minutes.
From Portsmouth & Southsea train to Southampton Central. 41 min £12. From Portsmouth, The Hard bus to Southampton City Centre, Coach Station. 45 min £3. From Portsmouth taxi to Southampton. 25 min £51. From Portsmouth drive to Southampton. 25 min £3. From Portsmouth rideshare to Southampton. 42 min £3.